feat(auth): implement authentication service, guards, and interceptors

- Add AuthService for handling login, registration, and session management.
- Create auth guards to protect routes based on authentication status.
- Implement auth interceptor to attach JWT token to HTTP requests and handle 401 errors.
- Add unit tests for AuthService, guards, and interceptor.
- Create login and registration components with form validation and error handling.
- Update routing to include guards for login and registration pages.

src/app/app.routes.spec.ts

@@ -1,14 +1,15 @@
-import { signal } from '@angular/core';
+import { computed, signal } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
 import { provideRouter, Router } from '@angular/router';
 
 import { of } from 'rxjs';
 
 import { App } from './app';
-import { routes } from './app.routes';
+import { AuthService } from './core/services/auth/auth.service';
+import { CartService } from './core/services/cart/cart.service';
 import { Tenant } from './core/services/tenant.interface';
 import { TenantService } from './core/services/tenant.service';
-import { CartService } from './core/services/cart/cart.service';
+import { routes } from './app.routes';
 
 const tenant: Tenant = {
   id: 1,
@@ -47,9 +48,33 @@ function createTenantServiceStub(
   };
 }
 
+function createAuthServiceStub(isAuthenticated = false) {
+  const tokenState = signal<string | null>(isAuthenticated ? 'test-token' : null);
+  const userState = signal(
+    isAuthenticated ? { id: 1, nombre_apellido: 'Ada Lovelace', email: 'ada@example.com' } : null
+  );
+
+  return {
+    user: userState.asReadonly(),
+    token: tokenState.asReadonly(),
+    isAuthenticated: computed(() => tokenState() !== null),
+    login: vi.fn(),
+    register: vi.fn(),
+    logout: vi.fn(),
+    loadCurrentUser: vi.fn(),
+    hydrateSession: vi.fn(),
+    bootstrap: vi.fn().mockResolvedValue(undefined),
+    clearSession: vi.fn(() => {
+      userState.set(null);
+      tokenState.set(null);
+    })
+  };
+}
+
 async function renderAppAt(
   url: string,
-  tenantService: ReturnType<typeof createTenantServiceStub> = createTenantServiceStub()
+  tenantService: ReturnType<typeof createTenantServiceStub> = createTenantServiceStub(),
+  authService: ReturnType<typeof createAuthServiceStub> = createAuthServiceStub()
 ) {
   TestBed.resetTestingModule();
 
@@ -67,6 +92,10 @@ async function renderAppAt(
           cart: signal(null).asReadonly(),
           loadCart: () => of({ id: 1, items: [], subtotal: '0' })
         }
+      },
+      {
+        provide: AuthService,
+        useValue: authService
       }
     ]
   }).compileComponents();
@@ -112,33 +141,41 @@ describe('app routes', () => {
 
     expect(router.url).toBe('/login');
     expect(compiled.querySelector('app-login-page')).not.toBeNull();
-    expect(compiled.textContent).toContain('Iniciar sesión');
+    expect(compiled.textContent).toContain('Iniciar sesion');
     expect(compiled.textContent).toContain('Crear cuenta');
   });
 
   it('loads the register page at /register and renders the shared auth fields', async () => {
     const { fixture, router } = await renderAppAt('/register');
     const compiled = fixture.nativeElement as HTMLElement;
-    const placeholders = Array.from(compiled.querySelectorAll('input')).map((input) =>
+    const registerPage = compiled.querySelector('app-register-page');
+    const placeholders = Array.from(registerPage?.querySelectorAll('input') ?? []).map((input) =>
       input.getAttribute('placeholder')
     );
 
     expect(router.url).toBe('/register');
-    expect(compiled.querySelector('app-register-page')).not.toBeNull();
+    expect(registerPage).not.toBeNull();
     expect(compiled.textContent).toContain('CREAR CUENTA');
     expect(compiled.textContent).toContain('Volver');
     expect(placeholders).toEqual([
       'Nombre y Apellido',
       'Email',
-      'Contraseña',
-      'Repetir Contraseña'
+      'Contrasena',
+      'Repetir Contrasena'
     ]);
   });
 
+  it('redirects authenticated users away from /login', async () => {
+    const { router } = await renderAppAt('/login', createTenantServiceStub(), createAuthServiceStub(true));
+
+    expect(router.url).toBe('/');
+  });
+
   it('renders the tenant not found screen for any route when the tenant is missing', async () => {
     const { fixture } = await renderAppAt(
       '/componentes-test/reutilizables',
-      createTenantServiceStub('not-found', null)
+      createTenantServiceStub('not-found', null),
+      createAuthServiceStub()
     );
     const compiled = fixture.nativeElement as HTMLElement;