feat: Implement comprehensive multi-channel notification system with templating and SSL monitoring

- Add robust notification system supporting 7+ communication channels with intelligent message templating, resource monitoring, and SSL certificate alerts. Notification Channels: (Telegram, Discord, Slack, Signal, Email, Google Chat, Webhooks).

- This notification system provides enterprise-grade alerting capabilities with extensive customization options and multi-channel redundancy for critical service monitoring.

server/service-operation/notification/manager.go

@@ -0,0 +1,67 @@
+
+package notification
+
+import (
+	// "log"
+
+	"service-operation/pocketbase"
+)
+
+// NotificationManager handles all notification operations
+type NotificationManager struct {
+	pbClient      *pocketbase.PocketBaseClient
+	services      map[string]NotificationService
+	serverManager *ServerNotificationManager
+	uptimeManager *UptimeNotificationManager
+	sslManager    *SSLNotificationManager
+}
+
+// NewNotificationManager creates a new notification manager
+func NewNotificationManager(pbClient *pocketbase.PocketBaseClient) *NotificationManager {
+	// Initialize notification services
+	services := make(map[string]NotificationService)
+	
+	// log.Printf("🔧 Initializing notification services...")
+	services["telegram"] = NewTelegramService()
+	services["signal"] = NewSignalService()
+	services["discord"] = NewDiscordService()
+	services["slack"] = NewSlackService()
+	services["google_chat"] = NewGoogleChatService()
+	services["email"] = NewEmailService()
+	services["webhook"] = NewWebhookService()
+
+	// log.Printf("✅ Notification services initialized: %v", getKeys(services))
+
+	// Create specialized managers
+	serverManager := NewServerNotificationManager(pbClient, services)
+	uptimeManager := NewUptimeNotificationManager(pbClient, services)
+	sslManager := NewSSLNotificationManager(pbClient, services)
+
+	return &NotificationManager{
+		pbClient:      pbClient,
+		services:      services,
+		serverManager: serverManager,
+		uptimeManager: uptimeManager,
+		sslManager:    sslManager,
+	}
+}
+
+// SendServiceNotification sends notification for a service based on its configuration
+func (nm *NotificationManager) SendServiceNotification(payload *NotificationPayload, notificationID, templateID string) error {
+	return nm.serverManager.SendServiceNotification(payload, notificationID, templateID)
+}
+
+// SendResourceNotification sends notification for specific resource alerts (CPU, RAM, Disk, etc.)
+func (nm *NotificationManager) SendResourceNotification(payload *NotificationPayload, notificationID, templateID, resourceType string) error {
+	return nm.serverManager.SendResourceNotification(payload, notificationID, templateID, resourceType)
+}
+
+// SendUptimeServiceNotification sends notification for uptime services using service templates
+func (nm *NotificationManager) SendUptimeServiceNotification(payload *NotificationPayload, notificationID, templateID string) error {
+	return nm.uptimeManager.SendUptimeServiceNotification(payload, notificationID, templateID)
+}
+
+// SendSSLNotification sends notification for SSL certificates using SSL templates
+func (nm *NotificationManager) SendSSLNotification(payload *NotificationPayload, notificationID, templateID string) error {
+	return nm.sslManager.SendSSLNotification(payload, notificationID, templateID)
+}