feat: Hub monitoring takeover — event push system + config cleanup (v0.21.0)

Replace external Healthchecks.io with Hub-native event system. Controller
now pushes structured events via POST /api/v1/event with typed detail
structs. Hub handles dead man's switch, notification dispatch, and cooldowns.

Phase 5: PushEvent() core method, 21 event types, expanded notification
settings (11 toggles), Hub connection monitoring on dashboard, alerts.
Phase 6: Deprecation log for ping UUIDs, pinger kept for transition.

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

controller/internal/web/alerts.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"strings"
 	"sync"
+	"time"
 
 	"gitea.dooplex.hu/admin/felhom-controller/internal/backup"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
@@ -27,9 +28,10 @@ type Alert struct {
 // Alerts are state-based (not event-based) — they reflect current system state
 // and are regenerated after each health check cycle.
 type AlertManager struct {
-	mu     sync.RWMutex
-	alerts []Alert
-	logger *log.Logger
+	mu              sync.RWMutex
+	alerts          []Alert
+	logger          *log.Logger
+	hubPushStatusFn func() HubPushStatusData
 }
 
 // NewAlertManager creates a new AlertManager.
@@ -39,6 +41,13 @@ func NewAlertManager(logger *log.Logger) *AlertManager {
 	}
 }
 
+// SetHubPushStatus sets the hub push status callback for generating hub alerts.
+func (am *AlertManager) SetHubPushStatus(fn func() HubPushStatusData) {
+	am.mu.Lock()
+	am.hubPushStatusFn = fn
+	am.mu.Unlock()
+}
+
 // Refresh regenerates alerts from the latest health check report and config state.
 // Called after each health check cycle (every 5 minutes) and on storage state changes.
 func (am *AlertManager) Refresh(report *monitor.HealthReport, cfg *config.Config, backupMgr *backup.Manager, updateAvailable bool, latestVersion string, storagePaths ...[]settings.StoragePath) {
@@ -92,14 +101,22 @@ func (am *AlertManager) Refresh(report *monitor.HealthReport, cfg *config.Config
 		alerts = append(alerts, alert)
 	}
 
-	// Missing ping UUIDs
-	if cfg.Monitoring.Enabled {
-		missing := countMissingPings(cfg)
-		if missing > 0 {
+	// Hub connection status
+	if !cfg.Hub.Enabled || cfg.Hub.URL == "" {
+		alerts = append(alerts, Alert{
+			ID:       "hub-disabled",
+			Level:    "warning",
+			Message:  "Hub kapcsolat kikapcsolva — a központi monitoring nem aktív",
+			Link:     "/monitoring",
+			LinkText: "Rendszermonitor",
+		})
+	} else if am.hubPushStatusFn != nil {
+		ps := am.hubPushStatusFn()
+		if ps.LastError != "" && (ps.LastSuccess.IsZero() || time.Since(ps.LastSuccess) > 30*time.Minute) {
 			alerts = append(alerts, Alert{
-				ID:       "pings-missing",
-				Level:    "warning",
-				Message:  fmt.Sprintf("%d monitoring ellenőrzés nincs beállítva", missing),
+				ID:       "hub-unreachable",
+				Level:    "error",
+				Message:  fmt.Sprintf("Hub nem elérhető — utolsó hiba: %s", ps.LastError),
 				Link:     "/monitoring",
 				LinkText: "Rendszermonitor",
 			})
@@ -200,24 +217,6 @@ func (am *AlertManager) GetInlineAlerts(page string) []Alert {
 	return result
 }
 
-// countMissingPings counts how many ping UUIDs are not configured.
-func countMissingPings(cfg *config.Config) int {
-	count := 0
-	uuids := []string{
-		cfg.Monitoring.PingUUIDs.Heartbeat,
-		cfg.Monitoring.PingUUIDs.SystemHealth,
-		cfg.Monitoring.PingUUIDs.DBDump,
-		cfg.Monitoring.PingUUIDs.Backup,
-		cfg.Monitoring.PingUUIDs.BackupIntegrity,
-	}
-	for _, uuid := range uuids {
-		if !isPingConfigured(uuid) {
-			count++
-		}
-	}
-	return count
-}
-
 // simpleHash returns a short deterministic hash for deduplication.
 func simpleHash(s string) string {
 	h := uint32(0)