Three notification channels:
- sync_progress (LOW): foreground notification while syncing, shows pair name
- sync_complete (LOW): result after success — "↑X ↓X" or "Up to date"
- sync_alerts (DEFAULT): error notification with message on failure
Notifications respect per-pair notifyOnComplete / notifyOnError settings.
All notifications tap-through to MainActivity. Foreground info now names the
pair being synced instead of the generic "Syncing…" text.
Bump to 1.0.14 (code 15).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>