chore: document external audio follow-ups

Co-authored-by: OpenCode (gpt-5.6-sol) <noreply@opencode.ai>

Author: hi-ogawa

packages/youtube-external-audio/src/lib/external-audio-panel.tsx

@@ -18,6 +18,8 @@ export function ExternalAudioPanel({
   getVideo: () => VideoClock | null | undefined;
 }) {
   // TODO: Add a floating open/close button and persist panel state per video.
+  // TODO: Persist the chosen audio per video, following ytsub-v5's per-video
+  // state pattern.
   const inputRef = useRef<HTMLInputElement>(null);
   const audioRef = useRef<HTMLAudioElement>(null);
   const syncRef = useRef<PlayerSync>(null);

packages/youtube-external-audio/src/lib/player-sync.ts

@@ -39,6 +39,8 @@ export class PlayerSync {
 
     this.#originalMuted = this.video.muted;
     this.#enabled = true;
+    // TODO: YouTube sometimes clears video.muted during playback. Investigate
+    // how its own mute control keeps the player muted and mirror that behavior.
     this.video.muted = true;
     this.#alignTime();
     this.#alignRate();

packages/youtube-external-audio/src/web.tsx

@@ -13,6 +13,7 @@ class FakeVideo extends EventTarget implements VideoClock {
 
 const fakeVideo = new FakeVideo();
 
+// TODO: Add Playwright coverage for the standalone panel preview.
 function Web() {
   const [dark, setDark] = useState(false);