fix(jellyfin): show overlay, inject plugin, and fix stats title on playb

- Show visible overlay automatically during Jellyfin playback so subtitleStyle applies
- Inject bundled mpv plugin on auto-launch so keybindings work without overlay focus
- Group Jellyfin playback stats under item metadata (jellyfin://host/item/id) instead of stream URLs so episodes merge with matching local titles
- Mark ffsubsync unavailable in subsync modal for remote media paths
- Drain queued second-instance commands even when onReady throws

launcher/mpv.test.ts

@@ -819,6 +819,7 @@ test('startOverlay uses caller config dir for app control socket discovery', asy
   const { dir, socketPath } = createTempSocketPath();
   const configDir = path.join(dir, 'launcher-config');
   const controlSocketPath = getAppControlSocketPath({ configDir, platform: 'linux' });
+  fs.mkdirSync(configDir, { recursive: true });
   const appPath = path.join(dir, 'fake-subminer.sh');
   const appInvocationsPath = path.join(dir, 'app-invocations.log');
   const receivedControlArgv: string[][] = [];