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/index.css

@@ -0,0 +1,47 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+:root {
+  color-scheme: dark;
+}
+
+html,
+body,
+#root {
+  height: 100%;
+}
+
+body {
+  background: radial-gradient(
+      ellipse at 20% 50%,
+      rgba(0, 240, 255, 0.08) 0%,
+      transparent 50%
+    ),
+    radial-gradient(
+      ellipse at 80% 20%,
+      rgba(168, 85, 247, 0.08) 0%,
+      transparent 50%
+    ),
+    #060a13;
+  color: #f5f7fa;
+  margin: 0;
+}
+
+@layer components {
+  .glass-panel {
+    @apply rounded-2xl border border-white/10 bg-surface-800/60 p-6 shadow-lg backdrop-blur-md;
+  }
+
+  .neon-button {
+    @apply inline-flex items-center justify-center gap-2 rounded-lg border border-primary-400/40
+      bg-primary-400/10 px-4 py-2 font-medium text-primary-400 transition
+      hover:border-primary-400 hover:bg-primary-400/20 hover:text-white
+      active:scale-95 disabled:cursor-not-allowed disabled:opacity-50;
+  }
+
+  .input-base {
+    @apply w-full rounded-lg border border-white/10 bg-surface-900/60 px-4 py-2 text-sm
+      text-white placeholder:text-slate-500 focus:border-primary-400 focus:outline-none;
+  }
+}