v2: mpegts.js + single-upstream fan-out hub (no FFmpeg/HLS)

Replaces the FFmpeg -> MediaMTX -> HLS pipeline with a raw MPEG-TS
fan-out architecture:

- Go stream.Hub holds ONE upstream connection per active channel and
  broadcasts the raw TS bytes to all connected browsers via /ts.
  The IPTV provider only ever sees one IP (the server), no matter how
  many viewers are watching (shared single-channel model).
- Frontend uses mpegts.js to play the raw TS in-browser via MSE,
  fixing HEVC/H.265 4K streams that HLS could not package.
- Dropped FFmpeg, MediaMTX, RTMP/RTSP, HLS proxy, playback/ingest
  modes, the OBS source toggle, and FFmpeg health stats.
- UI look preserved (fullscreen video, collapsible sidebar, status
  bar, upstream-down banner, hourly playlist auto-refresh).

Tradeoff: loses iOS Safari (no MSE/mpegts.js); fixes desktop/Android
playback of both H.264 and H.265.

frontend/src/App.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback, useRef } from "react";
-import type { StreamStatus, Channel, PlaybackMode } from "./types";
+import type { StreamStatus, Channel } from "./types";
 import * as api from "./api/client";
 import Player from "./components/Player";
 import StatusBar from "./components/StatusBar";
@@ -17,23 +17,9 @@ export default function App() {
   const [status, setStatus] = useState<StreamStatus | null>(null);
   const [channels, setChannels] = useState<Channel[]>([]);
   const [sidebarOpen, setSidebarOpen] = useState(false);
-  const [playbackMode, setPlaybackMode] = useState<PlaybackMode>("standard");
   const [toggleVisible, setToggleVisible] = useState(false);
   const hideTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
 
-  useEffect(() => {
-    api
-      .getConfig()
-      .then((c) => {
-        if (c.playback_mode === "llhls" || c.playback_mode === "fmp4") {
-          setPlaybackMode(c.playback_mode);
-        } else {
-          setPlaybackMode("standard");
-        }
-      })
-      .catch(() => {});
-  }, []);
-
   const fetchStatus = useCallback(async () => {
     try {
       const s = await api.getStatus();
@@ -56,7 +42,7 @@ export default function App() {
     fetchStatus();
     fetchChannels();
     // Poll faster while live so passive viewers detect channel switches promptly.
-    // Transitioning gets the fastest rate so the UI clears quickly after FFmpeg starts.
+    // Transitioning gets the fastest rate so the UI clears quickly after a switch.
     const rate = status?.transitioning ? 1000 : status?.live ? 2000 : 5000;
     const interval = setInterval(fetchStatus, rate);
     return () => clearInterval(interval);
@@ -103,10 +89,6 @@ export default function App() {
     }
   }, [showToggle]);
 
-  const handleSourceChanged = () => {
-    fetchStatus();
-  };
-
   const handlePlaylistReloaded = () => {
     fetchChannels();
   };
@@ -121,8 +103,7 @@ export default function App() {
       <div className="stage">
         <Player
           live={status?.live ?? false}
-          mode={playbackMode}
-          streamKey={`${status?.source ?? "offline"}:${status?.channel_name ?? ""}`}
+          streamKey={status?.channel_name ?? "offline"}
         />
       </div>
 
@@ -138,11 +119,7 @@ export default function App() {
 
       <aside className={`sidebar ${sidebarOpen ? "open" : "collapsed"}`}>
         <div className="sidebar-inner">
-          <AdminPanel
-            status={status}
-            onSourceChanged={handleSourceChanged}
-            onPlaylistReloaded={handlePlaylistReloaded}
-          />
+          <AdminPanel onPlaylistReloaded={handlePlaylistReloaded} />
           <ChannelList
           channels={channels}
           activeChannel={status?.channel_name ?? ""}