Machine status probe on page load:
- POST /api/machines/refresh probes all machines in parallel (max 20 concurrent, 1.5s timeout)
- Updates DB status and broadcasts via SSE to all connected browser tabs
- Server-side throttle: ignores refresh requests within 10s
- Machines.tsx and Dashboard.tsx fire probe on mount
- Visual "Checking machine status..." indicator in Machines table
- MachineHandler now accepts *Engine for ProbeAllMachines access
darroyo
1798fc6804