Configure ESLint with deprecation checking and fix all lint violations

frontend/src/app/app.spec.ts

@@ -14,8 +14,8 @@ describe('App', () => {
       hasValidAccessToken: () => false,
       getIdentityClaims: () => null,
       getAccessToken: () => 'mock-token',
-      initCodeFlow: () => {},
-      logOut: () => {}
+      initCodeFlow: vi.fn(),
+      revokeTokenAndLogout: vi.fn()
     };
 
     mockHttpClient = {
@@ -77,7 +77,7 @@ describe('App', () => {
     const app = fixture.componentInstance;
 
     const loginSpy = vi.spyOn(mockOAuthService, 'initCodeFlow');
-    const logoutSpy = vi.spyOn(mockOAuthService, 'logOut');
+    const logoutSpy = vi.spyOn(mockOAuthService, 'revokeTokenAndLogout');
 
     app.login();
     expect(loginSpy).toHaveBeenCalled();
@@ -106,7 +106,6 @@ describe('App', () => {
 
   it('should render logged in state when user is authenticated', async () => {
     const fixture = TestBed.createComponent(App);
-    const app = fixture.componentInstance;
     
     // Log in
     mockOAuthService.hasValidAccessToken = () => true;