feat(queen): Add proper daemon supervisor with PID tracking #430

Problem

Queen daemon lacks proper supervision — no heartbeat monitoring, auto-restart, or health tracking.

Requirements

1. PID tracking — queen.pid file with process lifecycle
2. Health monitor — periodic heartbeat checks
3. Auto-restart — restart on crash (with backoff)
4. Graceful shutdown — SIGTERM handling with cleanup
5. Status command — tri queen status shows real state

Implementation Plan

Phase 1: PID File

// .trinity/queen/queen.pid
{
  "pid": 12345,
  "started_at": 1773945606,
  "heartbeat": 1774273571
}

Phase 2: Monitor Loop

• Read PID file every 30s
• Check if process exists (kill -0)
• If dead: log, wait, restart (exponential backoff)

Phase 3: Signal Handling

• SIGTERM: graceful shutdown (save state, close connections)
• SIGINT: same as SIGTERM
• SIGHUP: reload config

Phase 4: Status Command

tri queen status
# → Running: ✓ | PID: 12345 | Uptime: 3d 2h | Heartbeat: 5s ago

Success Criteria

• PID file created on start, removed on exit
• Monitor detects dead Queen within 30s
• Auto-restart with max 3 retries/hour
• tri queen status shows accurate info
• Graceful shutdown saves state

References

• Doctor: ./zig-out/bin/queens doctor
• State: .trinity/queen_state.json

φ² + 1/φ² = 3 = TRINITY