feat: NCS-63 User account implementation (#2)

User Profile info, no game before login/register, menu bar

---------

Co-authored-by: Lala, Shahd <Shahd.Lala@sybit.de>
Co-authored-by: shahdlala66 <shahd.lala66@gmail.com>
Reviewed-on: #2

src/app/services/auth.service.ts

@@ -0,0 +1,93 @@
+import { Injectable, inject } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { BehaviorSubject, Observable } from 'rxjs';
+import { map, tap } from 'rxjs/operators';
+import { environment } from '../../environments/environment';
+import { LoginRequest, RegisterRequest, RegisterResponse, LoginResponse, CurrentUser } from '../models/auth.models';
+
+@Injectable({ providedIn: 'root' })
+export class AuthService {
+  private readonly apiBase = environment.apiBaseUrl;
+  private readonly accountServiceUrl = environment.accountServiceUrl;
+  private readonly http = inject(HttpClient);
+
+  private currentUserSubject = new BehaviorSubject<CurrentUser | null>(null);
+  public currentUser$ = this.currentUserSubject.asObservable();
+
+  constructor() {
+    this.loadCurrentUser();
+  }
+
+  login(username: string, password: string): Observable<LoginResponse> {
+    return this.http
+      .post<LoginResponse>(`${this.accountServiceUrl}/api/account/login`, {
+        username,
+        password
+      })
+      .pipe(
+        tap((response) => {
+          localStorage.setItem('token', response.token);
+          localStorage.setItem('username', username);
+          // After login, fetch current user info
+          this.getCurrentUser().subscribe();
+        })
+      );
+  }
+
+  register(username: string, password: string, email?: string): Observable<RegisterResponse> {
+    return this.http
+      .post<RegisterResponse>(`${this.accountServiceUrl}/api/account`, {
+        username,
+        password,
+        email
+      })
+      .pipe(
+        tap((response) => {
+          localStorage.setItem('username', response.username);
+          localStorage.setItem('userId', response.id);
+          this.currentUserSubject.next({
+            id: response.id,
+            username: response.username,
+            rating: response.rating,
+            createdAt: response.createdAt
+          });
+        })
+      );
+  }
+
+  getCurrentUser(): Observable<CurrentUser> {
+    return this.http.get<CurrentUser>(`${this.accountServiceUrl}/api/account/me`).pipe(
+      tap((user) => {
+        localStorage.setItem('username', user.username);
+        localStorage.setItem('userId', user.id);
+        this.currentUserSubject.next(user);
+      })
+    );
+  }
+
+  logout(): void {
+    localStorage.removeItem('token');
+    localStorage.removeItem('username');
+    localStorage.removeItem('userId');
+    this.currentUserSubject.next(null);
+  }
+
+  isLoggedIn(): boolean {
+    return !!localStorage.getItem('token');
+  }
+
+  private loadCurrentUser(): void {
+    const token = localStorage.getItem('token');
+    const username = localStorage.getItem('username');
+    const userId = localStorage.getItem('userId');
+    if (token && username && userId) {
+      // Try to verify token is still valid by fetching current user
+      this.getCurrentUser().subscribe({
+        error: () => {
+          // Token is invalid, clear it
+          this.logout();
+        }
+      });
+    }
+  }
+}