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/api/status.go

@@ -0,0 +1,22 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// HandleStatus returns the current stream status as JSON.
+// GET /api/status
+func (a *App) HandleStatus(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	a.mu.RLock()
+	status := a.Status
+	a.mu.RUnlock()
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(status)
+}