feat: Implement TOTP-based Two-Factor Authentication

- Add django-otp and qrcode dependencies
- Create comprehensive 2FA views and templates in German
- Add 2FA setup, verification, and management interfaces
- Implement backup token system with 10 recovery codes
- Add TwoFactorMiddleware for session enforcement
- Integrate 2FA controls into user navigation menu
- Support QR code generation for authenticator apps
- Add forms for secure 2FA operations with validation
- Configure OTP settings and admin site integration

Features:
- Optional 2FA (users can enable/disable)
- TOTP compatible with Google Authenticator, Authy, etc.
- Backup codes for emergency access
- German language interface
- Session-based 2FA enforcement
- Password confirmation for sensitive operations
- Production-ready with HTTPS support

app/static.backup.20250929_221458/README.md

@@ -0,0 +1,11 @@
+# Static Files Directory
+
+This directory contains static files for the Django application.
+
+## Structure:
+- `css/` - Custom CSS files
+- `js/` - Custom JavaScript files  
+- `img/` - Image assets
+- `fonts/` - Font files
+
+Static files are collected to `staticfiles/` directory during deployment via `python manage.py collectstatic`.