feat: Fix MongoDB connection and improve health check

- Fixed environment variable handling for MongoDB (MONGO_URI/MONGODB_URI)
- Enhanced health check endpoint to show environment variable status
- Updated deployment documentation with corrected environment variables
- Fixed npm ci issues in deployment pipeline
- Enhanced Telegram registration section in email templates
- Ready for deployment to new repository

Author: RabbitDaCoder

DEPLOY_GUIDE.md

@@ -8,7 +8,7 @@
 
 1. Go to [render.com](https://render.com) and sign up
 2. Connect your GitHub account
-3. Import your `ExpressLogistics` repository
+3. Import your `aegis-express` repository
 
 #### B. Create Web Service