Add Telegram bot integration for real-time alert notifications

- Implemented ITelegramNotificationService and TelegramNotificationService for sending alerts via Telegram.
- Updated MonitoringSettings to include Telegram configuration options.
- Enhanced AlertService to send alerts and resolutions through Telegram.
- Added API endpoints for checking Telegram status and sending test alerts.
- Updated README and TELEGRAM_SETUP.md with setup instructions and features.
- Included example configuration in appsettings.telegram.example.json.

appsettings.json

@@ -88,7 +88,17 @@
         "DurationSeconds": 60,
         "IsEnabled": true
       }
-    ]
+    ],
+    "Telegram": {
+      "IsEnabled": true,
+      "BotToken": "7705627522:AAHDTVMF1uPJW7qm-Di0g_BmefAVWdOrS2U",
+      "ChatIds": [398126624],
+      "SendWarningAlerts": true,
+      "SendCriticalAlerts": true,
+      "SendResolutionNotifications": true,
+      "MessageTemplate": "🚨 *{Level} Alert*\n\n📊 *{Component}*\n💬 {Message}\n⏰ {Timestamp}",
+      "ResolutionTemplate": "✅ *Alert Resolved*\n\n📊 *{Component}*\n💬 {Message}\n⏰ Resolved at {ResolvedAt}"
+    }
   },
   "LoggingSettings": {
     "LogLevel": "Information",