v3.16.0 - Daemon Resilience & Auto-Recovery

Major stability improvements to prevent and recover from signal-cli daemon failures.

- TCP keepalive (10s) for faster dead connection detection
- 30-second heartbeat to detect unresponsive daemon
- Proactive reconnect on socket errors (EPIPE, ECONNRESET)
- Connection stats tracking for monitoring

- Circuit breaker prevents restart loops (max 5 in 5 min)
- Exponential backoff between restarts (2s to 60s)
- Auto-restart on daemon exit/error events
- Auto-restart on RPC disconnect
- Critical alerts when circuit breaker trips

1. TCP Keepalive (10s) → detects dead TCP connections
2. Heartbeat (30s) → detects unresponsive daemon
3. RPC Reconnect (5 attempts with backoff)
4. Daemon Watchdog (2 min) → backup health check
5. Circuit Breaker → prevents restart loops

- New VERIFICATION_CHECKLIST.md for operational verification
- Updated LESSONS_LEARNED.md with daemon failure patterns