feat: sharp edge pipeline V02, tessellation presets, media cache-bust, GMSH plan

Sharp Edge Pipeline V02:
- export_step_to_gltf.py: replace BRep_Tool.Polygon3D_s (returns None in XCAF) with
  GCPnts_UniformAbscissa curve sampling at 0.3mm step — extracts 17,129 segment pairs
- Inject sharp_edge_pairs + sharp_threshold_deg into GLB extras (scenes[0].extras)
  via binary GLB JSON-chunk patching (no extra dependency)
- export_gltf.py: read schaeffler_sharp_edge_pairs from Blender scene custom props,
  apply via KD-tree to mark edges sharp=True + seam=True (OCC mm Z-up → Blender transform)
- tools/restore_sharp_marks.py: dual-pass (dihedral angle + OCC pairs), updated coordinate
  transform (X, -Z, Y) * 0.001

Tessellation:
- Admin UI: Draft / Standard / Fine preset buttons with active-state highlighting
- Default angular deflection: preview 0.5→0.1 rad, production 0.2→0.05 rad
- export_glb.py: read updated defaults from system_settings

Media / Cache:
- media/service.py: get_download_url appends ?v={file_size_bytes} cache-buster
- media/router.py: Cache-Control: no-cache for all download/thumbnail endpoints

Render pipeline:
- still_render.py / turntable_render.py: shared GPU activation + camera improvements
- render_order_line.py: global render position support
- render_thumbnail.py: updated defaults

Frontend:
- InlineCadViewer: file_size_bytes-aware URL update triggers re-fetch on regeneration
- ThreeDViewer: material panel, part selection, PBR mode improvements
- Admin.tsx: tessellation preset cards, GMSH setting dropdown
- MediaBrowser, ProductDetail, OrderDetail, Orders: various UI improvements
- New: MaterialPanel, GlobalRenderPositionsPanel, StepIndicator components
- New: renderPositions.ts API client

Plans / Docs:
- plan.md: GMSH Frontal-Delaunay tessellation plan (6 tasks)
- LEARNINGS.md: OCC Polygon3D_s None issue + GCPnts fix
- .gitignore: add backend/core (core dump from root process)

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

frontend/src/api/orders.ts

@@ -2,6 +2,38 @@ import api from './client'
 import type { Product } from './products'
 import type { OutputType } from './outputTypes'
 
+export interface RenderLog {
+  renderer?: string
+  type?: string
+  format?: string
+  engine?: string
+  engine_used?: string
+  samples?: number
+  stl_quality?: string
+  smooth_angle?: number
+  total_duration_s?: number
+  stl_duration_s?: number
+  render_duration_s?: number
+  ffmpeg_duration_s?: number
+  stl_size_bytes?: number
+  output_size_bytes?: number
+  parts_count?: number
+  device_used?: string
+  compute_type?: string
+  gpu_fallback?: boolean
+  frame_count?: number
+  fps?: number
+  template?: string
+  lighting_only?: boolean
+  shadow_catcher?: boolean
+  material_replace?: boolean
+  fallback?: boolean
+  error?: string
+  started_at?: string
+  completed_at?: string
+  log_lines?: string[]
+}
+
 export interface OrderLine {
   id: string
   order_id: string
@@ -21,6 +53,9 @@ export interface OrderLine {
   unit_price: number | null
   render_position_id: string | null
   render_position_name: string | null
+  render_log: RenderLog | null
+  render_started_at: string | null
+  render_completed_at: string | null
   notes: string | null
   created_at: string
   updated_at: string
@@ -30,6 +65,7 @@ export interface OrderLineCreate {
   product_id: string
   output_type_id?: string | null
   render_position_id?: string | null
+  global_render_position_id?: string | null
   gewuenschte_bildnummer?: string | null
   notes?: string | null
 }