Fixes #277

What was done

• Enhanced winston.logger.ts:
  • Console transport with colored, human-readable output for development
  • JSON-formatted file transports for production (in /logs/ directory)
  • Daily rotating files via winston-daily-rotate-file — application-YYYY-MM-DD.log and error-YYYY-MM-DD.log
  • Max file size 20MB, auto-cleanup after 14-30 days
• New logger.middleware.ts:
  • Global NestJS middleware intercepting every incoming HTTP request
  • Logs format: [METHOD] [URL] - [IP] - [StatusCode] - [Elapsed MS]
  • Auto log level selection: error for 5xx, warn for 4xx, info for success
  • Redacts sensitive fields from request body: password, token, secret, apiKey, authorization, bearer, accessToken, refreshToken
  • IP sanitization (localhost alias, IPv6 mapping cleanup)
  • Skips logging request bodies larger than 10KB to prevent log bloat
• Updated LoggerModule: Now implements NestModule, applies middleware globally via configure()
• Added winston-daily-rotate-file dependency

How to verify

1. cd backend && npm install (to install winston-daily-rotate-file)
2. npm run start:dev
3. Make any HTTP request (e.g., GET /health)
4. Check console output: should see formatted log line like:
   2026-04-14 19:30:00 info: GET /health - localhost - 200 - 5ms
5. Set NODE_ENV=production and restart — logs will write to logs/application-YYYY-MM-DD.log and logs/error-YYYY-MM-DD.log
6. Send a POST with {"password": "secret", "token": "abc"} — verify it logs as {"password": "[REDACTED]", "token": "[REDACTED]"}