Auto-collapse inactive YouTube panel

public/app.js

@@ -56,7 +56,7 @@ function applyStoredWatchHeight() {
   if (savedHeight > 0) {
     stage.style.setProperty("--watch-panel-height", `${savedHeight}px`);
   }
-  setWatchCollapsed(localStorage.getItem(watchCollapsedStorageKey) === "true");
+  setWatchCollapsed(true);
 }
 
 function setWatchCollapsed(collapsed) {
@@ -327,9 +327,14 @@ async function applyWatchState(state) {
   if (!currentYoutubeVideoId) {
     youtubePlayer?.stopVideo?.();
     youtubeShell.classList.remove("is-active");
+    setWatchCollapsed(true);
     return;
   }
 
+  if (state.playing) {
+    setWatchCollapsed(false);
+  }
+
   youtubeShell.classList.add("is-active");
   const player = await ensureYoutubePlayer();
   applyingWatchStateUntil = Date.now() + 1200;