refactor(auth): replace UserService with AuthService usage

frontend/src/app/service/user.service.ts

@@ -1,51 +1,33 @@
 import { inject, Injectable } from '@angular/core';
-import { HttpClient } from '@angular/common/http';
-import { BehaviorSubject, catchError, EMPTY, Observable, tap } from 'rxjs';
-import { User } from '../model/User';
 import { AuthService } from '@service/auth.service';
+import { User } from '../model/User';
 
 @Injectable({
   providedIn: 'root',
 })
 export class UserService {
-  public currentUserSubject = new BehaviorSubject<User | null>(null);
-  public currentUser$ = this.currentUserSubject.asObservable();
-  private http: HttpClient = inject(HttpClient);
   private authService = inject(AuthService);
 
-  constructor() {
-    // Initialize with the current user from AuthService if available
-    const currentUser = this.authService.getUser();
-    if (currentUser) {
-      this.currentUserSubject.next(currentUser);
-    }
-
-    // Subscribe to auth service user updates
-    this.authService.userSubject.subscribe((user) => {
-      this.currentUserSubject.next(user);
-    });
-  }
-
-  public getCurrentUser(): Observable<User | null> {
-    return this.http.get<User | null>('/backend/users/me').pipe(
-      catchError(() => EMPTY),
-      tap((user) => this.currentUserSubject.next(user))
-    );
-  }
-
-  public refreshCurrentUser(): void {
-    this.getCurrentUser().subscribe();
-    this.authService.loadCurrentUser();
-  }
-
+  /**
+   * Updates the user's balance locally for immediate UI feedback
+   * This should be called before a server-side balance change is made
+   * The server update will be reflected when AuthService.loadCurrentUser() is called
+   */
   public updateLocalBalance(amount: number): void {
-    const currentUser = this.currentUserSubject.getValue();
+    const currentUser = this.authService.currentUserValue;
     if (currentUser) {
-      const updatedUser = {
+      const updatedUser: User = {
         ...currentUser,
         balance: currentUser.balance + amount,
       };
-      this.currentUserSubject.next(updatedUser);
+      this.authService.userSubject.next(updatedUser);
     }
   }
+  
+  /**
+   * Refreshes the current user's data from the server
+   */
+  public refreshCurrentUser(): void {
+    this.authService.loadCurrentUser();
+  }
 }