fix(jellyfin): send explicit hide/show overlay instead of toggle

- Track overlay visibility in plugin state; y-t uses explicit hide/show commands when state is known
- Prevent paused Jellyfin playback from resuming on overlay hide
- Fix subtitle cache cleanup to only remove dirs after successful cleanup

src/main/runtime/jellyfin-subtitle-preload.ts

@@ -235,9 +235,11 @@ export function createPreloadJellyfinExternalSubtitlesHandler(deps: {
 
   function cleanupActiveCache(): void {
     const dirs = [...activeCacheDirs];
-    activeCacheDirs.clear();
     if (dirs.length === 0) return;
     deps.cleanupCachedSubtitles(dirs);
+    for (const dir of dirs) {
+      activeCacheDirs.delete(dir);
+    }
   }
 
   const runPreload = async (params: {