feat(phase7.1): add HelpTooltip system with contextual help icons

- New HelpTooltip component: hover-triggered floating panel, themed via
  CSS variables, supports top/right/bottom/left positioning, no deps
- New helpTexts.ts registry: 14 entries covering render settings,
  admin actions, template fields, and wizard fields
- Admin.tsx: tooltips on Cycles/EEVEE samples, smooth angle, regenerate
  thumbnails, process unprocessed
- RenderTemplateTable.tsx: tooltips on material replace, lighting only,
  shadow catcher column headers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/HelpTooltip.tsx

@@ -0,0 +1,95 @@
+import { HelpCircle } from 'lucide-react'
+import { useState } from 'react'
+import { HELP_TEXTS, type HelpText } from '../help/helpTexts'
+
+interface HelpTooltipProps {
+  helpKey?: string
+  help?: HelpText
+  position?: 'top' | 'right' | 'bottom' | 'left'
+  size?: number
+}
+
+export function HelpTooltip({
+  helpKey,
+  help: directHelp,
+  position = 'right',
+  size = 14,
+}: HelpTooltipProps) {
+  const [visible, setVisible] = useState(false)
+  const help = directHelp ?? (helpKey ? HELP_TEXTS[helpKey] : undefined)
+
+  if (!help) return null
+
+  const tooltipPositionStyle: React.CSSProperties = (() => {
+    switch (position) {
+      case 'top':
+        return { bottom: '100%', left: '50%', transform: 'translateX(-50%)', marginBottom: 6 }
+      case 'bottom':
+        return { top: '100%', left: '50%', transform: 'translateX(-50%)', marginTop: 6 }
+      case 'left':
+        return { right: '100%', top: '50%', transform: 'translateY(-50%)', marginRight: 6 }
+      case 'right':
+      default:
+        return { left: '100%', top: '50%', transform: 'translateY(-50%)', marginLeft: 6 }
+    }
+  })()
+
+  return (
+    <span
+      className="relative inline-flex items-center"
+      onMouseEnter={() => setVisible(true)}
+      onMouseLeave={() => setVisible(false)}
+    >
+      <HelpCircle
+        size={size}
+        className="text-content-muted hover:text-content-secondary transition-colors cursor-help"
+      />
+
+      {visible && (
+        <div
+          className="absolute z-50 rounded-lg border shadow-lg p-3 text-sm"
+          style={{
+            ...tooltipPositionStyle,
+            backgroundColor: 'var(--color-bg-surface, var(--color-surface, #fff))',
+            borderColor: 'var(--color-border-default, #e5e7eb)',
+            color: 'var(--color-text-content, var(--color-content, #111827))',
+            maxWidth: 280,
+            minWidth: 180,
+            whiteSpace: 'normal',
+            pointerEvents: 'none',
+          }}
+        >
+          <p className="font-semibold mb-1" style={{ color: 'var(--color-text-content, inherit)' }}>
+            {help.title}
+          </p>
+          <p className="text-xs leading-relaxed" style={{ color: 'var(--color-content-secondary, #6b7280)' }}>
+            {help.body}
+          </p>
+          {help.unit && help.range && (
+            <p className="text-xs mt-1" style={{ color: 'var(--color-content-muted, #9ca3af)' }}>
+              Range: {help.range[0]}–{help.range[1]} {help.unit}
+            </p>
+          )}
+          {help.recommendation && (
+            <p
+              className="text-xs mt-1.5 px-2 py-1 rounded"
+              style={{ backgroundColor: 'rgba(16, 185, 129, 0.1)', color: 'var(--color-status-success-text, #065f46)' }}
+            >
+              Recommended: {help.recommendation}
+            </p>
+          )}
+          {help.warning && (
+            <p
+              className="text-xs mt-1.5 px-2 py-1 rounded"
+              style={{ backgroundColor: 'rgba(245, 158, 11, 0.1)', color: 'var(--color-status-warning-text, #92400e)' }}
+            >
+              Warning: {help.warning}
+            </p>
+          )}
+        </div>
+      )}
+    </span>
+  )
+}
+
+export default HelpTooltip

frontend/src/components/admin/RenderTemplateTable.tsx

@@ -1,6 +1,7 @@
 import { useState, useRef } from 'react'
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
 import { Pencil, Trash2, Plus, Check, X, Upload, Download } from 'lucide-react'
+import HelpTooltip from '../HelpTooltip'
 import { toast } from 'sonner'
 import {
   listRenderTemplates,
@@ -165,9 +166,24 @@ export default function RenderTemplateTable() {
               <th className="px-3 py-2 font-medium">Category</th>
               <th className="px-3 py-2 font-medium">Output Type</th>
               <th className="px-3 py-2 font-medium">Collection</th>
-              <th className="px-3 py-2 font-medium">Mat. Replace</th>
+              <th className="px-3 py-2 font-medium">
-              <th className="px-3 py-2 font-medium">Lighting Only</th>
+                <span className="inline-flex items-center gap-1">
-              <th className="px-3 py-2 font-medium" title="Enable Shadowcatcher collection (Cycles only)">Shadow Catcher</th>
+                  Mat. Replace
+                  <HelpTooltip helpKey="template.material_replace_enabled" position="bottom" size={12} />
+                </span>
+              </th>
+              <th className="px-3 py-2 font-medium">
+                <span className="inline-flex items-center gap-1">
+                  Lighting Only
+                  <HelpTooltip helpKey="template.lighting_only" position="bottom" size={12} />
+                </span>
+              </th>
+              <th className="px-3 py-2 font-medium">
+                <span className="inline-flex items-center gap-1">
+                  Shadow Catcher
+                  <HelpTooltip helpKey="template.shadow_catcher" position="bottom" size={12} />
+                </span>
+              </th>
               <th className="px-3 py-2 font-medium" title="Rotate camera around product instead of product rotation (faster GPU rendering)">Cam Orbit</th>
               <th className="px-3 py-2 font-medium">.blend File</th>
               <th className="px-3 py-2 font-medium">Active</th>

frontend/src/help/helpTexts.ts

@@ -0,0 +1,83 @@
+export interface HelpText {
+  title: string
+  body: string
+  warning?: string
+  recommendation?: string
+  unit?: string
+  range?: [number, number]
+}
+
+export const HELP_TEXTS: Record<string, HelpText> = {
+  // Render settings
+  'setting.blender_cycles_samples': {
+    title: 'Cycles Samples',
+    body: 'Number of render samples per pixel. Higher = better quality, longer render time.',
+    recommendation: '256 for production, 64 for quick previews',
+    unit: 'samples',
+    range: [1, 4096],
+  },
+  'setting.blender_eevee_samples': {
+    title: 'EEVEE Samples',
+    body: 'Anti-aliasing samples for EEVEE Next renderer. EEVEE is much faster than Cycles but less photorealistic.',
+    recommendation: '64 for standard quality',
+    unit: 'samples',
+    range: [1, 1024],
+  },
+  'setting.blender_smooth_angle': {
+    title: 'Smooth Shading Angle',
+    body: 'Angle threshold for auto-smooth shading on imported meshes. Below this angle, faces appear smooth; above it, edges show a sharp crease.',
+    recommendation: '30° works well for most bearings',
+    unit: 'degrees',
+    range: [0, 180],
+  },
+  'setting.thumbnail_renderer': {
+    title: 'Thumbnail Renderer',
+    body: 'Which renderer to use for STEP file thumbnails. Blender produces photorealistic results; Three.js is faster but lower quality.',
+    recommendation: 'Use Blender for production, Three.js for fast previews',
+  },
+  'setting.stl_quality': {
+    title: 'STL Export Quality',
+    body: 'Controls tessellation precision when converting STEP to STL for older render paths. High quality = finer mesh, larger file, slower conversion.',
+    recommendation: 'Low is sufficient for most thumbnails',
+  },
+  'action.regenerate_thumbnails': {
+    title: 'Regenerate All Thumbnails',
+    body: 'Re-renders thumbnails for all STEP files using current renderer settings. Queues every file on the thumbnail_rendering worker.',
+    warning: 'This queues a large number of tasks. Only run during off-peak hours.',
+  },
+  'action.process_unprocessed': {
+    title: 'Process Unprocessed',
+    body: "Queues all STEP files that have status 'pending' or 'failed' for metadata extraction and thumbnail rendering.",
+  },
+  'action.generate_missing_stls': {
+    title: 'Generate Missing STL Caches',
+    body: "Creates STL cache files for STEP files that don't have them yet. STL caches speed up repeated renders.",
+  },
+  'action.seed_aliases': {
+    title: 'Seed Material Aliases',
+    body: 'Loads the default Schaeffler material alias mappings (Steel→SCHAEFFLER_010101_Steel-Bare, etc). Safe to run multiple times — existing aliases are not overwritten.',
+  },
+  // Template fields
+  'template.lighting_only': {
+    title: 'Lighting Only Mode',
+    body: 'When enabled, this template provides only the world/HDRI lighting environment. The camera position is computed automatically from the product bounding box, ignoring any camera set up in the .blend file.',
+    recommendation: 'Use for HDR light-setup templates where you want auto-framing',
+  },
+  'template.shadow_catcher': {
+    title: 'Shadow Catcher',
+    body: "Adds a transparent ground plane that catches shadows from the product. Requires a 'Shadowcatcher' collection in the .blend file. Enables the transparent film option.",
+  },
+  'template.material_replace_enabled': {
+    title: 'Material Replacement',
+    body: 'When enabled, Blender will replace part materials with the mapped Schaeffler library materials. When disabled, the original .blend materials are used.',
+  },
+  // Wizard fields
+  'wizard.output_type': {
+    title: 'Output Type',
+    body: 'Defines what to render: still image, turntable animation, or custom output. Each output type has its own render settings and pricing.',
+  },
+  'wizard.render_template': {
+    title: 'Render Template',
+    body: 'A .blend file that provides lighting, camera setup, and optionally a background environment. Templates are matched by product category.',
+  },
+}

frontend/src/pages/Admin.tsx

@@ -5,6 +5,7 @@ import { UserPlus, Trash2, Pencil, ChevronDown, ChevronUp, ChevronRight, Setting
 import { Link } from 'react-router-dom'
 import api from '../api/client'
 import ConfirmModal from '../components/ConfirmModal'
+import HelpTooltip from '../components/HelpTooltip'
 import TemplateEditor from '../components/admin/TemplateEditor'
 import PricingTierTable from '../components/admin/PricingTierTable'
 import OutputTypeTable from '../components/admin/OutputTypeTable'
@@ -388,7 +389,10 @@ export default function AdminPage() {
               {/* Sample counts */}
               <div className="grid grid-cols-2 gap-4 max-w-sm">
                 <div>
-                  <label className="block text-xs font-medium text-content-secondary mb-1">Cycles samples</label>
+                  <label className="flex items-center gap-1 text-xs font-medium text-content-secondary mb-1">
+                    Cycles samples
+                    <HelpTooltip helpKey="setting.blender_cycles_samples" position="top" size={12} />
+                  </label>
                   <input
                     type="number"
                     min={1} max={4096} step={32}
@@ -400,7 +404,10 @@ export default function AdminPage() {
                   <p className="text-xs text-content-muted mt-0.5">Higher = better quality, slower</p>
                 </div>
                 <div>
-                  <label className="block text-xs font-medium text-content-secondary mb-1">EEVEE samples</label>
+                  <label className="flex items-center gap-1 text-xs font-medium text-content-secondary mb-1">
+                    EEVEE samples
+                    <HelpTooltip helpKey="setting.blender_eevee_samples" position="top" size={12} />
+                  </label>
                   <input
                     type="number"
                     min={1} max={1024} step={16}
@@ -415,7 +422,10 @@ export default function AdminPage() {
 
               {/* Smooth by angle */}
               <div className="flex items-center gap-4 flex-wrap">
-                <span className="text-sm font-medium text-content-secondary w-28 shrink-0">Smooth angle</span>
+                <span className="flex items-center gap-1 text-sm font-medium text-content-secondary w-28 shrink-0">
+                  Smooth angle
+                  <HelpTooltip helpKey="setting.blender_smooth_angle" size={12} />
+                </span>
                 <input
                   type="number"
                   min={0} max={180} step={5}
@@ -674,27 +684,33 @@ export default function AdminPage() {
                 <p className="text-xs text-content-muted">Resets files stuck in 'processing' to 'failed'. Runs automatically every 5 min.</p>
               </div>
               <div className="flex flex-col gap-1">
+                <div className="flex items-center gap-1.5">
                   <button
                     onClick={() => processUnprocessedMut.mutate()}
                     disabled={processUnprocessedMut.isPending}
-                  className="btn-secondary text-sm w-full justify-start"
+                    className="btn-secondary text-sm flex-1 justify-start"
                     title="Queue all pending and failed STEP files that have never been successfully processed"
                   >
                     <RefreshCw size={14} className={processUnprocessedMut.isPending ? 'animate-spin' : ''} />
                     {processUnprocessedMut.isPending ? 'Queueing…' : 'Process Unprocessed'}
                   </button>
+                  <HelpTooltip helpKey="action.process_unprocessed" position="left" />
+                </div>
                 <p className="text-xs text-content-muted">Queues all pending/failed STEP files for initial processing.</p>
               </div>
               <div className="flex flex-col gap-1">
+                <div className="flex items-center gap-1.5">
                   <button
                     onClick={() => regenerateMut.mutate()}
                     disabled={regenerateMut.isPending}
-                  className="btn-secondary text-sm w-full justify-start"
+                    className="btn-secondary text-sm flex-1 justify-start"
                     title="Re-render thumbnails for all completed CAD files using the current Blender settings"
                   >
                     <RefreshCw size={14} className={regenerateMut.isPending ? 'animate-spin' : ''} />
                     {regenerateMut.isPending ? 'Re-queuing…' : 'Regenerate All Thumbnails'}
                   </button>
+                  <HelpTooltip helpKey="action.regenerate_thumbnails" position="left" />
+                </div>
                 <p className="text-xs text-content-muted">Re-renders thumbnails for all completed CAD files.</p>
               </div>
               <div className="flex flex-col gap-1">