[BUG]: Refactor auth controller and fix issues

[zaibamachhaliya]

Current auth controller has several issues that need improvement.

Issues Found:

1. Security Issues:

   • Password stored temporarily in pendingSignups Map (plain text)
   • No rate limiting on OTP requests
   • No logout functionality

2. Validation Issues:

   • Password validation regex missing in some places
   • No validation for OTP format

3. Code Structure:

   • Mixed responsibilities (Appwrite + MySQL)
   • No separation of concerns
   • Hardcoded values (10 min expiry)
   • Missing error handling in db operations

4. Missing Features:

   • No logout endpoint
   • No change password endpoint
   • No session management
   • No email verification status in DB

5. Potential Bugs:

   • pendingSignups Map has no cleanup for failed verifications
   • Appwrite DB createDocument may fail silently
   • No transaction support for MySQL + Appwrite operations

Suggestions:

• Move OTP logic to separate service
• Add rate limiter for OTP endpoints
• Add logout endpoint
• Add change password endpoint
• Add proper error handling
• Use environment variables for expiry times
• Add session tracking in DB
• Add email_verified column in users table

Files: controllers/authController.js, config/db.js

[zaibamachhaliya]

Hi @mintainer
please assign to me this issue
Thank you!