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_home.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+import re
+
 import pytest
 from playwright.sync_api import Page, expect
 
@@ -9,9 +11,7 @@ from playwright.sync_api import Page, expect
 @pytest.mark.e2e
 def test_homepage_title_contains_brand(page: Page, base_url: str) -> None:
     page.goto(f"{base_url}/", wait_until="networkidle")
-    expect(page).to_have_title(lambda t: "No Hype AI" in t or len(t) > 0)
-    # At minimum the page must load without error
-    assert page.url.startswith(base_url)
+    expect(page).to_have_title(re.compile("No Hype AI"))
 
 
 @pytest.mark.e2e