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/fraction.js/fraction.d.ts

@@ -0,0 +1,60 @@
+declare module 'Fraction';
+
+export interface NumeratorDenominator {
+  n: number;
+  d: number;
+}
+
+type FractionConstructor = {
+  (fraction: Fraction): Fraction;
+  (num: number | string): Fraction;
+  (numerator: number, denominator: number): Fraction;
+  (numbers: [number | string, number | string]): Fraction;
+  (fraction: NumeratorDenominator): Fraction;
+  (firstValue: Fraction | number | string | [number | string, number | string] | NumeratorDenominator, secondValue?: number): Fraction;
+};
+
+export default class Fraction {
+  constructor (fraction: Fraction);
+  constructor (num: number | string);
+  constructor (numerator: number, denominator: number);
+  constructor (numbers: [number | string, number | string]);
+  constructor (fraction: NumeratorDenominator);
+  constructor (firstValue: Fraction | number | string | [number | string, number | string] | NumeratorDenominator, secondValue?: number);
+
+  s: number;
+  n: number;
+  d: number;
+
+  abs(): Fraction;
+  neg(): Fraction;
+
+  add: FractionConstructor;
+  sub: FractionConstructor;
+  mul: FractionConstructor;
+  div: FractionConstructor;
+  pow: FractionConstructor;
+  gcd: FractionConstructor;
+  lcm: FractionConstructor;
+  
+  mod(n?: number | string | Fraction): Fraction;
+
+  ceil(places?: number): Fraction;
+  floor(places?: number): Fraction;
+  round(places?: number): Fraction;
+
+  inverse(): Fraction;
+  
+  simplify(eps?: number): Fraction;
+  
+  equals(n: number | string | Fraction): boolean;
+  compare(n: number | string | Fraction): number;
+  divisible(n: number | string | Fraction): boolean;
+  
+  valueOf(): number;
+  toString(decimalPlaces?: number): string;
+  toLatex(excludeWhole?: boolean): string;
+  toFraction(excludeWhole?: boolean): string;
+  toContinued(): number[];
+  clone(): Fraction;
+}