Features:
- Cursor usage without the tokscale CLI: Syrtis downloads your usage itself, using the Cursor app's login on this Mac. A card on the Overview asks first (only if Cursor is installed); after Continue it syncs at launch and every 30 minutes. The login goes only to cursor.com and is never saved; Syrtis stores the date, model, token counts, cost and conversation ID of each request, and turning it off deletes them. Settings -> General -> Cursor usage sync has the switch and Sync Now. If the tokscale CLI already has Cursor data, Settings asks before Syrtis uses its own sync, so usage is counted once.

Fixes:
- Cursor usage synced by a recent tokscale CLI (saved as usage.json) is now read. Thanks @whes1015.
