fix: resolve 5 E2E test failures from first CI run

- test_homepage_title_contains_brand: to_have_title() requires a string or
  regex, not a lambda; switch to re.compile('No Hype AI')
- test_granular_preferences_save_dismisses_banner: wrong element clicked to
  open <details>; use 'details summary' locator directly
- test_subscribe_invalid_email_shows_error: browser HTML5 email validation
  swallows the submit event before the JS handler fires; add 'novalidate' via
  evaluate() so the fetch still runs and the server returns 400
- test_copy_link_button_updates_text: clipboard API unavailable in headless
  Docker; add polyfill + pre-grant permissions in conftest page fixture so
  the JS success path runs and button text becomes 'Copied'
- test_comments_section_absent_when_disabled: guard against Wagtail's
  add_child() resetting BooleanField defaults by calling an explicit
  .update(comments_enabled=False) + re-setting on the instance before
  save_revision().publish(); also tighten test to assert 200 + correct title

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

e2e/test_comments.py

@@ -48,6 +48,12 @@ def test_empty_body_shows_form_errors(page: Page, base_url: str) -> None:
 @pytest.mark.e2e
 def test_comments_section_absent_when_disabled(page: Page, base_url: str) -> None:
     """Article with comments_enabled=False must not show the comments section."""
-    page.goto(f"{base_url}/articles/e2e-no-comments/", wait_until="networkidle")
+    response = page.goto(f"{base_url}/articles/e2e-no-comments/", wait_until="networkidle")
+    assert response is not None and response.status == 200, (
+        f"Expected 200 for e2e-no-comments article, got {response and response.status}"
+    )
+    # Confirm we're on the right page
+    expect(page.get_by_role("heading", level=1)).to_have_text("No Comments Article")
+    # Comments section must be absent
     expect(page.get_by_role("heading", name="Comments")).to_have_count(0)
     expect(page.get_by_role("button", name="Post comment")).to_have_count(0)