Add MemorySampler that polls active worker PIDs every 10s to sample
/proc/<pid>/status for VmRSS, VmPeak, and VmSwap memory metrics.
Changes:
- Add MemorySampler class with periodic sampling (10s interval)
- Attach rssKb, peakRssKb, swapKb to WorkerState in types.ts
- Integrate with InMemoryEventStore to register PIDs from events
- Expose memory fields on GET /api/workers response
- Broadcast updated memory fields via WebSocket
- Add comprehensive test suite
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
