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>

apps/gacha/src/routes/__root.tsx

@@ -0,0 +1,18 @@
+import { createRootRoute, Outlet } from '@tanstack/react-router'
+import { Navbar } from '@imphnen-frontend-service/ui/organisms'
+import { ModalLoginProvider } from '@imphnen-frontend-service/utils'
+
+export const Route = createRootRoute({
+  component: RootLayout,
+})
+
+function RootLayout() {
+  return (
+    <ModalLoginProvider>
+      <main className="bg-primary-50 min-h-screen">
+        <Navbar />
+        <Outlet />
+      </main>
+    </ModalLoginProvider>
+  )
+}