Radio starts empty and fills from the Store (Add to Radio, including The Journey FM); iCloud connect falls back to the calendar home beside the principal

- Store > Radio is the station finder with Add to Radio / Added; Radio under Listen lists only what was added
- Fix the Radio tab going blank (the router passed its arguments as the Store host)
- iCloud: when the account reports no calendar home, try /<id>/calendars/, and say what iCloud answered if that fails

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v52';
+const CACHE = 'hub-v53';
 const SHARE = 'hub-share'; // files shared into the app from other apps, held until the person picks a folder
 const SHELL = ['/icon.svg', '/manifest.webmanifest', '/icons/icon-192.png', '/icons/apple-touch-icon.png'];