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>

frontend/src/App.tsx

@@ -0,0 +1,69 @@
+import { useState, useEffect, useCallback } from "react";
+import type { StreamStatus, Channel } from "./types";
+import * as api from "./api/client";
+import Player from "./components/Player";
+import StatusBar from "./components/StatusBar";
+import AdminPanel from "./components/AdminPanel";
+import ChannelList from "./components/ChannelList";
+import "./App.css";
+
+export default function App() {
+  const [status, setStatus] = useState<StreamStatus | null>(null);
+  const [channels, setChannels] = useState<Channel[]>([]);
+
+  const fetchStatus = useCallback(async () => {
+    try {
+      const s = await api.getStatus();
+      setStatus(s);
+    } catch {
+      // backend unreachable
+    }
+  }, []);
+
+  const fetchChannels = useCallback(async () => {
+    try {
+      const ch = await api.getChannels();
+      setChannels(ch);
+    } catch {
+      // backend unreachable
+    }
+  }, []);
+
+  useEffect(() => {
+    fetchStatus();
+    fetchChannels();
+    const interval = setInterval(fetchStatus, 5000);
+    return () => clearInterval(interval);
+  }, [fetchStatus, fetchChannels]);
+
+  const handleSourceChanged = () => {
+    fetchStatus();
+  };
+
+  const handlePlaylistReloaded = () => {
+    fetchChannels();
+  };
+
+  const handleChannelRefresh = () => {
+    fetchStatus();
+  };
+
+  return (
+    <div className="app">
+      <Player />
+      <StatusBar status={status} />
+      <div className="controls">
+        <AdminPanel
+          status={status}
+          onSourceChanged={handleSourceChanged}
+          onPlaylistReloaded={handlePlaylistReloaded}
+        />
+        <ChannelList
+          channels={channels}
+          activeChannel={status?.channelName ?? ""}
+          onRefresh={handleChannelRefresh}
+        />
+      </div>
+    </div>
+  );
+}