- Fix frontend Logs.vue to use correct field names (entity_type, entity_name, old_value, new_value)
- Add user and source_ip columns to logs table
- Add details column showing old_value -> new_value transitions
- Fix backend logs API to support pagination (page, page_size, search)
- Add search support across all log fields (action, entity_type, entity_name, username, values)
- Return proper {list, total, page, page_size} response format
- Login/Logout: record user authentication events with source IP
- Login failed: record failed login attempts for security audit
- Export: record data export operations
- Machine status change: record online/offline transitions with reason
- SSH sync: record automatic SSH sync success/failure with error details
- All auto-generated logs use username='system' and empty source_ip
- Split SSH sync from ping loop into independent service
- Ping service: serial polling, 30s interval, only updates online status
- SSH sync service: runs every 10 minutes for all online machines
- Global semaphore limits concurrent SSH to 2 (prevents resource exhaustion)
- SSH command timeout 8s prevents hanging on unresponsive hosts
- Offline machines are skipped for SSH sync
- Ping fallback: if ping fails but SSH succeeds, mark as online (SSH sync handles info)
- Change ping interval from 60s to 30s (configurable via PING_INTERVAL)
- Change SSH info sync from every ping to every 10 minutes (via ssh_synced_at)
- Add SSH command timeout (8s) to prevent hanging on unresponsive hosts
- Add concurrency limit (5) for SSH sync operations
- Change frontend UI refresh interval from 10s to 30s
- Fix: remove hardcoded 30s step, use configured interval directly
- Fix: ensure ping loop continues even if individual machine fails