feat(L1): modular widget dashboard — 15 configurable widgets

Replaces monolithic AdminDashboard/ClientDashboard with a per-user
configurable widget grid. 15 widget types: ProductionStats, QueueStatus,
RecentRenders, CostOverview, WorkerStatus, KPISummary, OrderThroughput,
Revenue, ItemStatus, ProcessingTimes, RenderTimeByOutputType,
OutputTypeUsage, TopProducts, OrdersByUser, RenderBackendStats.

DashboardTimeframeContext provides shared timeframe state. Dashboard
config persisted in DB via GET/PUT /api/dashboard/config.

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

frontend/src/pages/Dashboard.tsx

@@ -1,22 +1,10 @@
-import { useAuthStore } from '../store/auth'
 import DashboardGrid from '../components/dashboard/DashboardGrid'
-import AdminDashboard from '../components/dashboard/AdminDashboard'
-import ClientDashboard from '../components/dashboard/ClientDashboard'
 
 export default function DashboardPage() {
-  const user = useAuthStore((s) => s.user)
-  const isPrivileged = user?.role === 'admin' || user?.role === 'project_manager'
-
   return (
-    <div className="space-y-8">
-      {/* Configurable widget grid — visible to all roles */}
-      <div className="p-8 pb-0">
-        <h1 className="text-2xl font-bold text-content mb-6">Dashboard</h1>
-        <DashboardGrid />
-      </div>
-
-      {/* Role-based analytics section */}
-      {isPrivileged ? <AdminDashboard /> : <ClientDashboard />}
+    <div className="p-8">
+      <h1 className="text-2xl font-bold text-content mb-6">Dashboard</h1>
+      <DashboardGrid />
     </div>
   )
 }