fix: harden media handoff and live logs

Reject stale extension media cookie headers before yt-dlp metadata work, preserve ordinary capture cookies, and advance the companion extension.

Stream redacted diagnostic logs only while the visible Logs view is active, with bounded batched updates and race-safe snapshot handoff.

src/App.tsx

@@ -397,6 +397,12 @@ function App() {
     invoke('toggle_log_pause', { pause: !logsEnabled }).catch(console.error);
   }, [logsEnabled]);
 
+  useEffect(() => {
+    if (activeView !== 'logs') {
+      invoke('set_log_stream_active', { active: false }).catch(console.error);
+    }
+  }, [activeView]);
+
   useEffect(() => {
     if (!extensionPairingToken) return;
     invoke('set_extension_pairing_token', { token: extensionPairingToken }).catch(error => {