- Add 10 alert criteria types with RPC-based evaluation and 24h rolling cooldown
- Implement pluggable email service with Gmail SMTP and unsubscribe links
- Add ALERT_SUBSCRIPTION query classification and isolated 2-tool resolution
- Add confirmation, unsubscribe, and internal evaluate API routes
- Add background evaluator, digest sender, and cleanup workers
- Add comprehensive test suite with 45 unit tests and 44 simulated tool tests
