feat: migrate all 5 Vite apps from react-router to TanStack Router

Migrated backoffice, hackathon, dimentorin, gacha, qrcampaign, and
infra from custom react-router file-based routing to TanStack Router
file-based routing following the tanstack-frontend-best-practice
convention.

Key changes per app:
- New routes/ directory with __root.tsx, _public.tsx, _authenticated.tsx
- Auth guards via beforeLoad (replaces old middleware.ts)
- createFileRoute pattern for all page components
- TanStackRouterVite plugin in vite.config for auto route generation
- _components/_hooks folders colocated with routes (ignored by router)
- routeTree.gen.ts auto-generated on dev/build

Convention:
- _public/* routes redirect to dashboard if authenticated
- _authenticated/* routes redirect to /auth/login if not authenticated
- $param for dynamic segments (was [param] in old convention)
- _layout suffix for pathless layout routes

Removed:
- Old src/app/ directories from all apps
- Old src/middleware.ts files
- Custom convertPagesToRoute utility (no longer needed)
- react-router dependency usage (kept in package.json for shared libs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -46,8 +46,10 @@
     "@redocly/ajv": "^8.18.1",
     "@tailwindcss/vite": "^4.2.2",
     "@tanstack/react-query": "^5.95.2",
+    "@tanstack/react-router": "^1.168.13",
     "@tanstack/react-store": "^0.9.3",
     "@tanstack/react-table": "^8.21.3",
+    "@tanstack/router-plugin": "^1.167.12",
     "astro": "^6.1.5",
     "axios": "^1.14.0",
     "class-variance-authority": "^0.7.1",