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/pages/SearchPage.tsx

@@ -0,0 +1,42 @@
+import { ChangeEvent, useEffect, useState } from 'react'
+
+import { mediaAPI } from '../api/library'
+import { MediaCard } from '../components/MediaCard'
+import type { Media } from '../types'
+
+// Search-as-you-type with a 300ms debounce.
+export function SearchPage() {
+  const [q, setQ] = useState('')
+  const [items, setItems] = useState<Media[]>([])
+  const [loading, setLoading] = useState(false)
+
+  useEffect(() => {
+    const t = setTimeout(() => {
+      setLoading(true)
+      mediaAPI
+        .search(q, 60)
+        .then((d) => setItems(d.items))
+        .finally(() => setLoading(false))
+    }, 300)
+    return () => clearTimeout(t)
+  }, [q])
+
+  return (
+    <div className="space-y-6">
+      <h1 className="font-display text-3xl font-bold text-white">搜索</h1>
+      <input
+        autoFocus
+        className="input-base"
+        placeholder="按标题搜索…"
+        value={q}
+        onChange={(e: ChangeEvent<HTMLInputElement>) => setQ(e.target.value)}
+      />
+      {loading && <p className="text-slate-500">搜索中…</p>}
+      <div className="grid grid-cols-2 gap-4 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-5 xl:grid-cols-6">
+        {items.map((m) => (
+          <MediaCard key={m.id} media={m} />
+        ))}
+      </div>
+    </div>
+  )
+}