fix(anime): strip disguised HLS segments and report real playback errors

Some hosts prepend a fake image header (a real 1x1 PNG) to every HLS
segment; ffmpeg probes the segment as a picture and mpv drops back to
idle with no window while the browser claims the episode is playing.

- Route bridge-served m3u8 streams through a local strip proxy that
  scans each segment for the first genuine MPEG-TS packet run and drops
  the junk in front of it; playlists get absolute origins rewritten so
  segment requests come back through the proxy. Non-TS bodies pass
  through untouched.
- Only report ok from playEpisode once mpv configures a video output;
  an end-file with reason error surfaces mpv's own message (e.g. "no
  audio or video data played") in the browser status bar instead of
  "Playing". New end-file event plumbed through the mpv IPC client.

src/main.ts

@@ -3232,6 +3232,17 @@ const animeBrowserRuntime = createAnimeBrowserRuntime({
     }),
   sendMpvCommand: (command) => sendMpvCommandRuntime(appState.mpvClient, command),
   ensureMpvConnected: () => ensureMpvConnectedForPlayback(),
+  onPlaybackEndFile: (listener) => {
+    const client = appState.mpvClient;
+    if (!client) return () => {};
+    client.on('end-file', listener);
+    return () => client.off('end-file', listener);
+  },
+  readMpvProperty: (name) => {
+    const client = appState.mpvClient;
+    if (!client) return Promise.reject(new Error('mpv is not connected.'));
+    return client.requestProperty(name);
+  },
   showVisibleOverlay: () => {
     // Launching a video turns a browse-only instance into a regular SubMiner
     // playback session: tray icon plus the overlay runtime that