fixing linting and tests errors

app/__tests__/api/email.test.tsx

@@ -18,7 +18,7 @@ afterAll(() => {
 
 beforeEach(() => {
   nodemailermock.mock.reset();
-  process.env.MY_EMAIL = 'test@dki.one';
+  process.env.MY_EMAIL = 'test@dk0.dev';
   process.env.MY_PASSWORD = 'test-password';
 });
 
@@ -42,7 +42,7 @@ describe('POST /api/email', () => {
 
     const sentEmails = nodemailermock.mock.getSentMail();
     expect(sentEmails.length).toBe(1);
-    expect(sentEmails[0].to).toBe('contact@dki.one');
+    expect(sentEmails[0].to).toBe('contact@dk0.dev');
     expect(sentEmails[0].text).toContain('Hello! This is a test message.');
   });
 

app/__tests__/components/Header.test.tsx

@@ -5,7 +5,8 @@ import '@testing-library/jest-dom';
 describe('Header', () => {
   it('renders the header', () => {
     render(<Header />);
-    expect(screen.getByText('DK')).toBeInTheDocument();
+    expect(screen.getByText('dk')).toBeInTheDocument();
+    expect(screen.getByText('0')).toBeInTheDocument();
     
     const aboutButtons = screen.getAllByText('About');
     expect(aboutButtons.length).toBeGreaterThan(0);