fix: e2e test login form selectors

- Use specific email field ID to avoid ambiguity between password and magic link forms
- Use case-insensitive regex for 'Log in' button text

e2e/tests/auth.setup.ts

@@ -31,12 +31,12 @@ setup('authenticate', async ({ page }) => {
   // Navigate to login page
   await page.goto('/users/log-in');
 
-  // Fill in email and password
-  await page.getByLabel('Email').fill(email);
+  // Fill in email and password (use the password form, not magic link)
+  await page.locator('#user_email_password').fill(email);
   await page.getByLabel('Password').fill(password);
 
   // Submit login form
-  await page.getByRole('button', { name: 'Sign in' }).click();
+  await page.getByRole('button', { name: /log in/i }).click();
 
   // Wait for TOTP page
   await page.waitForURL('**/users/log-in/totp');