Implement Tuner v1 — Go backend, React frontend, Docker setup

- Go backend: REST API, M3U parser, FFmpeg/MediaMTX process manager
- React/Vite frontend: HLS player, admin panel, channel browser (dark theme)
- MediaMTX config for RTMP ingest + HLS output
- Multi-stage Dockerfile (Go + Bun + Alpine runtime)
- docker-compose.yml for single-container deployment
- Sample M3U playlist with test streams

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/main.go

@@ -0,0 +1,124 @@
+package main
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"tuner/api"
+	"tuner/m3u"
+	"tuner/process"
+)
+
+func getEnv(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}
+
+func main() {
+	playlistPath := getEnv("PLAYLIST_PATH", "/data/playlist.m3u")
+	mediamtxBin := getEnv("MEDIAMTX_PATH", "mediamtx")
+	mediamtxCfg := getEnv("MEDIAMTX_CONFIG", "mediamtx.yml")
+	port := getEnv("RESTREAMER_PORT", "8080")
+
+	// Initialize process managers
+	mtxManager := process.NewMediaMTXManager(mediamtxBin, mediamtxCfg)
+	ffmpegManager := process.NewFFmpegManager()
+
+	// Build shared app state
+	app := &api.App{
+		PlaylistPath: playlistPath,
+		MediaMTX:     mtxManager,
+		FFmpeg:       ffmpegManager,
+	}
+
+	// Load playlist (warn but don't crash if missing)
+	channels, err := m3u.ParseFile(playlistPath)
+	if err != nil {
+		log.Printf("[startup] warning: could not load playlist %s: %v", playlistPath, err)
+	} else {
+		app.Channels = channels
+		log.Printf("[startup] loaded %d channels from %s", len(channels), playlistPath)
+	}
+
+	// Start MediaMTX (warn but don't crash if binary not found)
+	if err := mtxManager.Start(); err != nil {
+		log.Printf("[startup] warning: could not start mediamtx: %v", err)
+	}
+
+	// Register routes
+	mux := http.NewServeMux()
+
+	// API routes
+	mux.HandleFunc("/api/status", app.HandleStatus)
+	mux.HandleFunc("/api/admin/channels", app.HandleChannels)
+	mux.HandleFunc("/api/admin/groups", app.HandleGroups)
+	mux.HandleFunc("/api/admin/source", app.HandleSetSource)
+	mux.HandleFunc("/api/admin/channel", app.HandleSetChannel)
+	mux.HandleFunc("/api/admin/playlist/reload", app.HandleReloadPlaylist)
+	mux.HandleFunc("/api/admin/process/status", app.HandleProcessStatus)
+
+	// Serve frontend static files (falls back to index.html for SPA routing)
+	frontendDir := getEnv("FRONTEND_DIR", "frontend/dist")
+	if info, err := os.Stat(frontendDir); err == nil && info.IsDir() {
+		fs := http.FileServer(http.Dir(frontendDir))
+		mux.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Try to serve the file; if it doesn't exist, serve index.html (SPA fallback)
+			path := frontendDir + r.URL.Path
+			if _, err := os.Stat(path); os.IsNotExist(err) && r.URL.Path != "/" {
+				http.ServeFile(w, r, frontendDir+"/index.html")
+				return
+			}
+			fs.ServeHTTP(w, r)
+		}))
+		log.Printf("[startup] serving frontend from %s", frontendDir)
+	} else {
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "text/plain")
+			w.Write([]byte("Tuner backend running. Frontend not found."))
+		})
+		log.Printf("[startup] frontend dir %s not found, serving placeholder", frontendDir)
+	}
+
+	// Wrap with middleware
+	handler := api.Logging(api.CORS(mux))
+
+	server := &http.Server{
+		Addr:    ":" + port,
+		Handler: handler,
+	}
+
+	// Graceful shutdown
+	go func() {
+		sigCh := make(chan os.Signal, 1)
+		signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+		sig := <-sigCh
+		log.Printf("[shutdown] received %v, shutting down...", sig)
+
+		// Stop child processes
+		if err := ffmpegManager.Stop(); err != nil {
+			log.Printf("[shutdown] error stopping ffmpeg: %v", err)
+		}
+		if err := mtxManager.Stop(); err != nil {
+			log.Printf("[shutdown] error stopping mediamtx: %v", err)
+		}
+
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if err := server.Shutdown(ctx); err != nil {
+			log.Printf("[shutdown] http server shutdown error: %v", err)
+		}
+	}()
+
+	log.Printf("[startup] listening on :%s", port)
+	if err := server.ListenAndServe(); err != http.ErrServerClosed {
+		log.Fatalf("[fatal] server error: %v", err)
+	}
+	log.Println("[shutdown] complete")
+}