Persist per-host scan results and expose hosts endpoint.

Store checked hosts for each scan and add API to fetch host-level up/down probe results.

Made-with: Cursor

internal/scans/runner.go

@@ -70,6 +70,11 @@ func (r *Runner) run(job ScanJob) {
 		defer wg.Done()
 		for ip := range workCh {
 			isUp := probeHost(ip, job.Options.PingTimeoutMS)
+			_ = r.store.SaveHostResult(job.ID, HostResult{
+				IP:        ip,
+				IsUp:      isUp,
+				CheckedAt: time.Now().UTC(),
+			})
 
 			mu.Lock()
 			done++