feat: initial prototype works

I can log in and create a book! Woo!

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

@@ -0,0 +1,55 @@
+/**
+ * @copyright 2026 NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { Injectable, signal } from '@angular/core';
+import { Router } from '@angular/router';
+import { Observable, tap } from 'rxjs';
+import { ApiService } from './api.service';
+import { AuthResponse, User } from '@library/shared-types';
+import { environment } from '../../environments/environment';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class AuthService {
+  private currentUser = signal<User | null>(null);
+  public readonly user = this.currentUser.asReadonly();
+
+  constructor(
+    private api: ApiService,
+    private router: Router
+  ) {}
+
+  login(): void {
+    // Redirect to API login endpoint
+    window.location.href = `${environment.apiUrl}/auth/login`;
+  }
+
+  getCurrentUser(): Observable<AuthResponse> {
+    return this.api.get<AuthResponse>('/auth/me').pipe(
+      tap(response => {
+        this.currentUser.set(response.user);
+      })
+    );
+  }
+
+  logout(): Observable<{ message: string }> {
+    return this.api.post<{ message: string }>('/auth/logout', {}).pipe(
+      tap(() => {
+        this.currentUser.set(null);
+        this.router.navigate(['/']);
+      })
+    );
+  }
+
+  isAuthenticated(): boolean {
+    return this.user() !== null;
+  }
+
+  isAdmin(): boolean {
+    return this.user()?.isAdmin === true;
+  }
+}