Add JWT support for authentication handling

Integrate `@auth0/angular-jwt` for Token management. Update `app.config.ts` with `JwtModule` setup and token getter from cookies. Enhance `AuthService` to include token handling, fake login, and JWT validation using `JwtHelperService`. Introduce `JwtClaims` interface for structured token claims.

frontend/src/app/services/auth.service.ts

@@ -4,6 +4,7 @@ import {CookieService} from 'ngx-cookie-service';
 import {BehaviorSubject, Observable, throwError} from 'rxjs';
 import {catchError, tap} from 'rxjs/operators';
 import {MatSnackBar} from '@angular/material/snack-bar';
+import {JwtHelperService} from '@auth0/angular-jwt';
 
 @Injectable({
   providedIn: 'root'
@@ -12,13 +13,14 @@ export class AuthService {
   private isAuthenticatedSubject = new BehaviorSubject<boolean>(false);
   public isAuthenticated$ = this.isAuthenticatedSubject.asObservable();
 
-  private userClaimsSubject = new BehaviorSubject<any>(null);
+  private userClaimsSubject = new BehaviorSubject<JwtClaims | null>(null);
   public userClaims$ = this.userClaimsSubject.asObservable();
 
   constructor(
     private loginService: LoginService,
     private cookieService: CookieService,
-    private snackBar: MatSnackBar
+    private snackBar: MatSnackBar,
+    private jwtHelper: JwtHelperService
   ) {
     // Check if user is already logged in on service initialization
     this.checkAuthStatus();
@@ -30,7 +32,7 @@ export class AuthService {
   public login(code: string): Observable<any> {
     return this.loginService.login(code).pipe(
       tap(jwt => {
-        this.saveJwt(jwt as JsonWebKey);
+        this.saveJwt(jwt);
         this.isAuthenticatedSubject.next(true);
       }),
       catchError(error => {
@@ -40,6 +42,13 @@ export class AuthService {
     );
   }
 
+  public fakeLogin(): Observable<any> {
+    const jwt = 'ZXlKaGJHY2lPaUpTVXpJMU5pSjkuZXlKcGMzTWlPaUpoYkhScGRIVmtaWGRsWWlJc0luTjFZaUk2SWpVMVpUUTJZbU16TFRKaE1qa3ROR00xTXkwNE5UQm1MV1JpWkRrME5HUmpOV00xWmlJc0ltVjRjQ0k2TVRjMU5ESTFNREUyTkN3aWFXRjBJam94TnpVeE5qVTRNVFkwTENKaGRYUm9iM0pwZEdsbGN5STZXeUpUUTA5UVJWOTFjMlZ5SWwxOS5iWU5Ba0hjUEp5ektReTl0cjN2RFB2VUNyX0FtQTNNVEtrZmlLV0dzV2M1QTdjR3ZKay1UYmQzdEJzYU1LZjI0ZUotZmtudjEyWFBGaXRXSmdRRVdNYTJvc19EYWkwZm1kT1J3MUlRb2d5bndOamtnWjBnMUJfU1lCMVRpZV9YQXpJTkNJSkNXMHB4YTB5U0dQUWxPaTJjVE1uWjdlRDlHMkI5NW0tcklMNG9NVDJMa3NwSjR2NXNCSlVrclNEaEl2dkQxOUhvWlFNV0VpU3BUbkQxVVhCSC1NVFVBMWhSSUFaZEd1cTVfWmpsQWNpMlpya195c0ZreGZBYVZHRW4zQXlpMFNmMjZhbEFlSGVxaW90M1lvWDR5djYyd0treThaODdkZVdMcWxvUHBzdi1INXNVX1E3dzhMano4cS1Ecl9hMHVRMlF2bDc4Y1RDV1JtTm04dlE=';
+    this.saveJwt(jwt);
+    this.isAuthenticatedSubject.next(true);
+    return undefined as any;
+  }
+
   /**
    * Log the user out by removing the JWT
    */
@@ -56,14 +65,13 @@ export class AuthService {
     const jwt = this.getJwt();
     if (jwt) {
       try {
-        const claims = this.extractJwtClaims(jwt as JsonWebKey);
         // Check if token is expired
-        const currentTime = Math.floor(Date.now() / 1000);
-        if (claims.exp && claims.exp < currentTime) {
+        if (this.jwtHelper.isTokenExpired(jwt)) {
           this.logout();
           return false;
         }
 
+        const claims = this.extractJwtClaims(jwt);
         this.userClaimsSubject.next(claims);
         this.isAuthenticatedSubject.next(true);
         return true;
@@ -84,8 +92,8 @@ export class AuthService {
   /**
    * Save the JWT to cookies
    */
-  private saveJwt(jwt: JsonWebKey): void {
-    this.cookieService.set('jwt', jwt.toString(), {
+  private saveJwt(jwt: string): void {
+    this.cookieService.set('jwt', jwt, {
       path: '/',
       secure: true,
       sameSite: 'Strict'
@@ -93,16 +101,14 @@ export class AuthService {
 
     const claims = this.extractJwtClaims(jwt);
     this.userClaimsSubject.next(claims);
+
   }
 
   /**
    * Extract claims from JWT
    */
-  private extractJwtClaims(jwt: JsonWebKey): any {
-    const token = jwt.toString();
-    const base64Url = token.split('.')[1];
-    const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/');
-    return JSON.parse(window.atob(base64));
+  private extractJwtClaims(jwt: string): JwtClaims {
+    return <JwtClaims>this.jwtHelper.decodeToken(jwt);
   }
 
   /**