feat: bootstrap MediaStationGo (Go + React rewrite of MediaStation)

Adopt the cropflre/nowen-video tech stack and rebuild the project from
scratch:

  - Backend: Go 1.25 + Gin + GORM + SQLite (WAL) + JWT + WebSocket hub.
    Layered packages config / database / model / repository / service /
    middleware / handler. Default admin (admin/admin123) seeded on first
    run; /api routes for auth, libraries, media, stream and admin
    panels. WebSocket scan-progress events at /api/ws.
  - Frontend: React 18 + Vite 5 + Tailwind 3.4 + Zustand + axios +
    react-router 6 + lucide-react + framer-motion + hls.js. Pages for
    Login / Home / Library / Search / MediaDetail / Player / Admin
    (Library, Users, Settings tabs).
  - Distribution: multi-arch Dockerfile (frontend -> backend -> Alpine
    runtime), docker-compose.yml, GitHub Actions for CI and GHCR
    publish, Makefile, env-prefixed config (MEDIASTATION_*).
  - Docs: README, CONTRIBUTING, .env.example, config.example.yaml.

Backend builds, vets and tests pass. Frontend builds via tsc -b && vite
build (250 kB JS / 16 kB CSS, gzipped 84 / 4 kB).

web/src/App.tsx

@@ -0,0 +1,56 @@
+import { Navigate, Route, Routes } from 'react-router-dom'
+
+import { Layout } from './components/Layout'
+import { RequireAuth, RequireAdmin } from './components/RequireAuth'
+import { AdminPage } from './pages/AdminPage'
+import { HomePage } from './pages/HomePage'
+import { LibraryPage } from './pages/LibraryPage'
+import { LoginPage } from './pages/LoginPage'
+import { MediaDetailPage } from './pages/MediaDetailPage'
+import { PlayerPage } from './pages/PlayerPage'
+import { SearchPage } from './pages/SearchPage'
+
+// Top-level route table.
+//
+// Public:
+//   /login
+//
+// Authenticated:
+//   /                      → home (continue watching + recently added)
+//   /library/:id           → library content grid
+//   /search                → keyword search
+//   /media/:id             → media detail
+//   /play/:id              → fullscreen player
+//
+// Admin only:
+//   /admin                 → users / settings / activity log
+export default function App() {
+  return (
+    <Routes>
+      <Route path="/login" element={<LoginPage />} />
+      <Route
+        path="/"
+        element={
+          <RequireAuth>
+            <Layout />
+          </RequireAuth>
+        }
+      >
+        <Route index element={<HomePage />} />
+        <Route path="library/:id" element={<LibraryPage />} />
+        <Route path="search" element={<SearchPage />} />
+        <Route path="media/:id" element={<MediaDetailPage />} />
+        <Route path="play/:id" element={<PlayerPage />} />
+        <Route
+          path="admin"
+          element={
+            <RequireAdmin>
+              <AdminPage />
+            </RequireAdmin>
+          }
+        />
+      </Route>
+      <Route path="*" element={<Navigate to="/" replace />} />
+    </Routes>
+  )
+}