PIV Image Sync Worker v5 (Three-Size Responsive Images + Event Logging)

Endpoints:
  GET  /health              Health check
  GET  /status              Sync progress
  GET  /logs/events         View sync event log (today)
  GET  /logs/events?date=YYYY-MM-DD  View specific date
  GET  /logs/events?event=villa_completed  Filter by event type
  GET  /logs?date=YYYY-MM-DD&limit=N  View completion logs
  POST /sync                Start/resume sync
  POST /sync?reset=true     Reset and restart
  POST /sync?trust=true     Skip HEAD checks (faster)
  POST /sync/pause          Pause sync
  POST /sync/resume         Resume sync
  POST /cleanup             Remove orphans
  POST /cleanup?dry=true    Preview orphan cleanup
  GET  /villas/*            Serve images

All POST endpoints require X-API-Key header.

v5 Changes:
  - Generates 3 sizes: thumb (640px), hero (1920px), full (2560px)
  - Stores actual dimensions for accurate srcset
  - Pause/resume endpoints for sync control
  - Immutable cache headers
  - Persistent event logs in R2