Async Kit - Phase 1, 2, 3 & 4

Endpoints:
- /test-briefing - Generate briefing (no send)
- /send-briefing - Generate and send briefing
- /webhook - Twilio webhook for incoming messages
- /sync-memory - Sync today's conversation to Notion
- /view-memory - View current memory and recent sessions
- /check-alerts - Check for Slack/Email alerts (Phase 3)
- /test-slack - Test Slack connection
- /auth/google - Connect Google account (Phase 4)
- /test-google - Test Google connection