User Login and JWT Authentication

[olaysco]

Implement login functionality and JWT token generation

Tasks:

• Create /api/auth/login POST endpoint
• Verify email/password combinations
• Generate JWT access tokens
• Create authentication decorators
• Add token validation middleware
• Create /api/auth/profile endpoint for user info

Acceptance Criteria:

• Users can login with correct credentials
• JWT tokens are generated and returned
• Protected endpoints require valid tokens
• Invalid credentials return proper errors
• Token expiration works correctly