Phase 2: monitoring warnings, dashboard alerts & notification system

- Monitoring page: "Távoli monitoring" section showing healthcheck ping UUID
  configuration status (configured/not configured) for each of the 5 pings
- Alert manager: persistent dashboard banners on all pages generated from
  health check results, missing pings, and backup status
- Notification system: controller-side notifier sends events to hub relay,
  with cooldown tracking and event-type filtering
- Notification preferences UI: email, event checkboxes, cooldown settings
  on the settings page with test email functionality
- Settings refactored: shared settingsData() helper, NotificationPrefs
  struct with getter/setter and defaults

New files:
- controller/internal/web/alerts.go (AlertManager)
- controller/internal/notify/notifier.go (hub notification client)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/cmd/controller/main.go

@@ -16,6 +16,7 @@ import (
 	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/metrics"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/monitor"
+	"gitea.dooplex.hu/admin/felhom-controller/internal/notify"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/report"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/scheduler"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
@@ -116,6 +117,12 @@ func main() {
 		go backupMgr.LoadSnapshotHistory()
 	}
 
+	// --- Initialize alert manager ---
+	alertMgr := web.NewAlertManager(logger)
+
+	// --- Initialize notifier ---
+	notifier := notify.New(cfg.Hub.URL, cfg.Hub.APIKey, cfg.Customer.ID, sett, logger)
+
 	// --- Initialize scheduler ---
 	sched := scheduler.New(logger)
 
@@ -147,16 +154,28 @@ func main() {
 		} else {
 			pinger.Ping(healthUUID, body)
 		}
+		// Refresh dashboard alerts from health report
+		alertMgr.Refresh(healthReport, cfg, backupMgr)
+		// Notify on health status changes
+		notifier.NotifyHealthChange(healthReport.Status, healthReport.Issues, healthReport.Warnings)
 		return nil
 	})
 
 	// Backup daily jobs
 	if cfg.Backup.Enabled && backupMgr != nil {
 		sched.Daily("db-dump", cfg.Backup.DBDumpSchedule, func(ctx context.Context) error {
-			return backupMgr.RunDBDumps(ctx)
+			err := backupMgr.RunDBDumps(ctx)
+			if err != nil {
+				notifier.NotifyDBDumpFailed("Adatbázis mentés sikertelen", err.Error())
+			}
+			return err
 		})
 		sched.Daily("backup", cfg.Backup.ResticSchedule, func(ctx context.Context) error {
-			return backupMgr.RunBackup(ctx)
+			err := backupMgr.RunBackup(ctx)
+			if err != nil {
+				notifier.NotifyBackupFailed("Biztonsági mentés sikertelen", err.Error())
+			}
+			return err
 		})
 
 		// Weekly integrity check — Sunday 04:00
@@ -164,7 +183,11 @@ func main() {
 			if time.Now().Weekday() != time.Sunday {
 				return nil
 			}
-			return backupMgr.RunIntegrityCheck(ctx)
+			err := backupMgr.RunIntegrityCheck(ctx)
+			if err != nil {
+				notifier.NotifyIntegrityFailed("Mentés integritás ellenőrzés sikertelen", err.Error())
+			}
+			return err
 		})
 
 		// Cache refresh: every 5 minutes
@@ -214,11 +237,17 @@ func main() {
 		}()
 	}
 
+	// Initial alert refresh (so alerts appear immediately, not after first 5min health check)
+	go func() {
+		report := monitor.RunHealthCheck(cfg, cpuCollector)
+		alertMgr.Refresh(report, cfg, backupMgr)
+	}()
+
 	// --- Initialize API router ---
 	apiRouter := api.NewRouter(cfg, stackMgr, syncer, cpuCollector, backupMgr, metricsStore, logger)
 
 	// --- Initialize web server ---
-	webServer := web.NewServer(cfg, stackMgr, cpuCollector, backupMgr, sched, sett, logger, Version)
+	webServer := web.NewServer(cfg, stackMgr, cpuCollector, backupMgr, sched, sett, alertMgr, notifier, logger, Version)
 
 	// --- Build HTTP mux ---
 	mux := http.NewServeMux()