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/app/node_modules/nanoid/nanoid.js

@@ -0,0 +1 @@
+export let nanoid=(t=21)=>crypto.getRandomValues(new Uint8Array(t)).reduce(((t,e)=>t+=(e&=63)<36?e.toString(36):e<62?(e-26).toString(36).toUpperCase():e<63?"_":"-"),"");