- Implemented `EmailOrUsernameBackend` to allow authentication via email or username
- Updated settings to include the new authentication backend
- Modified tests to cover email-based login scenarios
- Fixed user lookup logic in forms to handle case-insensitive email matching
- Updated `header.html` to use `with` block for `active` context variable fallback
- Added test to verify login page renders correctly without `active` context
- Added email templates for activation and password reset (`activation_email.html`, `password_reset_email.html`, etc.)
- Created forms for registration (`RegisterForm`) and login (`LoginForm`) with custom validation
- Developed new pages for account activation (`activation_success.html`, `activation_invalid.html`), password reset workflow, and profile
- Configured email backend and environment file handling in settings
- Updated header template to conditionally display profile or login links based on authentication status
- Enhanced CSS styles for authentication-related pages and forms
