refactor: Clean up logging system with LOG_LEVEL filtering

- Add LOG_LEVEL env variable support (debug, info, warn, error)
- Default to 'info' level for production-ready logs
- Integrate Morgan HTTP logging with custom logger
- Remove console.logs and replace with custom logger
- Remove sensitive password debug logs from email service
- Remove noisy warn logs from email sync and event notifier
- Add gray color for timestamps to improve readability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/index.js

@@ -1,9 +1,10 @@
 import app from './app.js';
 import { startAllCronJobs } from './cron/index.js';
+import { logger } from './utils/logger.js';
 
 const port = process.env.PORT || 5000;
 app.listen(port, () => {
-  console.log(`🚀 Server running on http://localhost:${port}`);
+  logger.info(`Server running on http://localhost:${port}`);
 
   // Start cron jobs after server is running
   startAllCronJobs();