T5/Phase 3: SPA shell + navigation

- TanStack Router with type-safe file-based routes
- Sidebar: collapsible, workspace switcher, 12 nav links, user menu
- Topbar: search, quick-add, notifications, user avatar
- cmdk command palette: nav + create + search + @mentions
- Keyboard shortcuts: Cmd+K palette, g+t/h/p/n/c/g/s navigation, ? help
- Theme: dark default, accent picker (slate/blue/green/purple/orange), persisted to localStorage
- Auth: login -> /, logout -> /login, 401 redirect
- Placeholder pages for all 13 nav routes (real in T6/T7)
- Typed API client with useApiQuery/useApiMutation hooks

apps/web/src/components/ui/aspect-ratio.tsx

@@ -0,0 +1,8 @@
+'use client';
+
+import * as React from 'react';
+import * as AspectRatioPrimitive from '@radix-ui/react-aspect-ratio';
+
+const AspectRatio = AspectRatioPrimitive.Root;
+
+export { AspectRatio };