feat: Major updates to backend structure and security enhancements

- Removed `COMMON_ERRORS.md` file to streamline documentation.
- Added `Flask-Limiter` for rate limiting and `redis` for session management in `requirements.txt`.
- Expanded `ROADMAP.md` to include completed security features and planned enhancements for version 2.2.
- Enhanced `setup_myp.sh` for ultra-secure kiosk installation, including system hardening and security configurations.
- Updated `app.py` to integrate CSRF protection and improved logging setup.
- Refactored user model to include username and active status for better user management.
- Improved job scheduler with uptime tracking and task management features.
- Updated various templates for a more cohesive user interface and experience.

backend/requirements.txt

@@ -4,6 +4,7 @@
 # Flask Framework und Extensions
 Flask==3.0.0
 Flask-Login==0.6.3
+Flask-Limiter==3.5.0
 
 # Datenbank
 SQLAlchemy==2.0.23
@@ -14,6 +15,10 @@ PyP100==0.1.2
 # Passwort-Hashing (bereits in Flask enthalten, aber explizit für Klarheit)
 Werkzeug==3.0.1
 
+# Sicherheit und Rate Limiting
+redis==5.0.1
+bcrypt==4.1.2
+
 # Entwicklung und Testing (optional)
 pytest==7.4.3
 pytest-cov==4.1.0