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).

internal/service/service.go

@@ -0,0 +1,48 @@
+// Package service contains the business logic of MediaStationGo. Handlers
+// deserialize the HTTP request, call into a Service method, then serialize
+// the response. Services own all cross-cutting policy (auth, scanning,
+// transcoding, etc.) and never deal with HTTP types directly.
+package service
+
+import (
+	"go.uber.org/zap"
+
+	"github.com/ShukeBta/MediaStationGo/internal/config"
+	"github.com/ShukeBta/MediaStationGo/internal/repository"
+)
+
+// Container holds every service initialized at startup. Handlers receive a
+// pointer to it and pick the relevant fields.
+type Container struct {
+	Cfg    *config.Config
+	Log    *zap.Logger
+	Repo   *repository.Container
+	WSHub  *Hub
+	Auth   *AuthService
+	Media  *MediaService
+	Scan   *ScannerService
+	Stream *StreamService
+}
+
+// New builds the service container.
+func New(cfg *config.Config, log *zap.Logger, repos *repository.Container) *Container {
+	hub := NewHub(log)
+	go hub.Run()
+	return &Container{
+		Cfg:    cfg,
+		Log:    log,
+		Repo:   repos,
+		WSHub:  hub,
+		Auth:   NewAuthService(cfg, log, repos),
+		Media:  NewMediaService(cfg, log, repos),
+		Scan:   NewScannerService(cfg, log, repos, hub),
+		Stream: NewStreamService(cfg, log, repos),
+	}
+}
+
+// Close releases any resources held by services (e.g. the websocket hub).
+func (c *Container) Close() {
+	if c.WSHub != nil {
+		c.WSHub.Stop()
+	}
+}