fix: improve webhook notifications for all providers

- Show full list of grouped alerts for Discord, Slack, Teams, etc (not just Telegram)
- Properly escape newlines in grouped alert messages to prevent JSON parsing errors
- Ensure consistent formatting across all webhook providers
- Address issue where only custom templates showed complete alert lists

All webhook providers now display the same detailed grouped alert format with bullet points showing each alert's resource and value.

internal/notifications/notifications.go

@@ -493,9 +493,16 @@ func (n *NotificationManager) sendGroupedWebhook(webhook WebhookConfig, alertLis
 		}
 		
 		if templateFound {
-			// Modify message if multiple alerts
+			// Modify message if multiple alerts - show full list with escaped newlines
 			if len(alertList) > 1 {
-				alert.Message = fmt.Sprintf("%s (and %d more alerts)", alert.Message, len(alertList)-1)
+				summary := alert.Message
+				otherAlerts := []string{}
+				for i := 1; i < len(alertList); i++ {
+					otherAlerts = append(otherAlerts, fmt.Sprintf("• %s: %.1f%%", alertList[i].ResourceName, alertList[i].Value))
+				}
+				if len(otherAlerts) > 0 {
+					alert.Message = fmt.Sprintf("%s\\n\\n🔔 All %d alerts:\\n%s", summary, len(alertList), strings.Join(otherAlerts, "\\n"))
+				}
 			}
 			
 			// Prepare data and generate payload