- FCMService now supports both HTTP v1 API (service account) and legacy API (server key)
- v1 API uses OAuth2 JWT auth with Firebase service account; tries this first
- Falls back to legacy HTTP API if only server key is configured
- Removes invalid tokens from DB automatically (NotRegistered, INVALID_ARGUMENT, etc.)
- AdminController now logs push result status and shows in UI response
- .env updated with FCM_SERVER_KEY placeholder and docs
- Migration 010 run in dev