- Added complete user management fields to User model:
* lastLoginAt for tracking user activity
* isActive for account status management
* emailVerified with verification token system
* failedLoginAttempts and lockedAt for security
* preferences, timezone, and preferredLanguage for UX
- Enhanced UserRepository with new management methods:
* updateLastLogin() with security features
* incrementFailedLoginAttempts() with auto-locking
* verifyEmail() for email verification workflow
* deactivateUser() and unlockUser() for admin management
* updatePreferences() for user settings
* improved findInactiveUsers() using lastLoginAt
- Updated database indexes for performance optimization
- Regenerated Prisma client with new schema
- Created comprehensive troubleshooting documentation
- Verified production build success with all enhancements