fix: escape newlines in grouped alert messages for JSON webhook templates

Webhooks weren't being sent because the grouped alert message contained actual
newlines which broke JSON parsing in custom templates. Changed to use escaped
newlines (\n) which work properly in JSON strings.

internal/notifications/notifications.go

@@ -195,7 +195,7 @@ func (n *NotificationManager) SendAlert(alert *alerts.Alert) {
 	n.mu.Lock()
 	defer n.mu.Unlock()
 	
-	log.Debug().
+	log.Info().
 		Str("alertID", alert.ID).
 		Bool("enabled", n.enabled).
 		Int("webhooks", len(n.webhooks)).
@@ -210,7 +210,7 @@ func (n *NotificationManager) SendAlert(alert *alerts.Alert) {
 	// Check cooldown
 	lastTime, exists := n.lastNotified[alert.ID]
 	if exists && time.Since(lastTime) < n.cooldown {
-		log.Debug().
+		log.Info().
 			Str("alertID", alert.ID).
 			Dur("timeSince", time.Since(lastTime)).
 			Dur("cooldown", n.cooldown).
@@ -445,7 +445,7 @@ func (n *NotificationManager) sendGroupedWebhook(webhook WebhookConfig, alertLis
 				otherAlerts = append(otherAlerts, fmt.Sprintf("• ... and %d more", len(alertList)-4))
 			}
 			if len(otherAlerts) > 0 {
-				alert.Message = fmt.Sprintf("%s\n\n🔔 Other alerts:\n%s", summary, strings.Join(otherAlerts, "\n"))
+				alert.Message = fmt.Sprintf("%s\\n\\n🔔 Other alerts:\\n%s", summary, strings.Join(otherAlerts, "\\n"))
 			}
 		}