feat: add comprehensive Playwright E2E test suite

- Create e2e/ directory with 7 test modules covering:
  - Home page: title, nav links, theme toggle, newsletter form
  - Cookie consent: accept all, reject all, granular prefs, persistence
  - Article index: loads, tag filter, click-through navigation
  - Article detail: title/read-time, share section, comments, newsletter aside, related
  - Comments: valid submit → redirect, empty body → error display, disabled check
  - Newsletter: JS confirmation message, invalid email error, aside form, duplicate
  - Feeds: RSS/sitemap/robots.txt validity, tag feed, seeded content present
- Extend seed_e2e_content management command with tagged article, about page,
  no-comments article, and legal pages for richer test coverage
- Add seed command tests (create + idempotency) to keep coverage ≥ 90%
- Add pr-e2e CI job (runs on pull_request): builds image, starts postgres + app,
  installs playwright, runs pytest e2e/
- Update nightly-e2e to run full e2e/ suite alongside legacy journey test
- Add --ignore=e2e to unit-test pytest step (coverage must not include browser tests)

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

apps/core/tests/test_commands.py

@@ -2,7 +2,7 @@ import pytest
 from django.core.management import call_command
 from django.core.management.base import CommandError
 
-from apps.blog.models import ArticleIndexPage, ArticlePage
+from apps.blog.models import AboutPage, ArticleIndexPage, ArticlePage
 from apps.blog.tests.factories import AuthorFactory
 
 
@@ -28,3 +28,29 @@ def test_check_content_integrity_fails_for_blank_summary(home_page):
 
     with pytest.raises(CommandError, match="empty summary"):
         call_command("check_content_integrity")
+
+
+@pytest.mark.django_db
+def test_seed_e2e_content_creates_expected_pages():
+    call_command("seed_e2e_content")
+
+    assert ArticlePage.objects.filter(slug="nightly-playwright-journey").exists()
+    assert ArticlePage.objects.filter(slug="e2e-tagged-article").exists()
+    assert ArticlePage.objects.filter(slug="e2e-no-comments").exists()
+    assert AboutPage.objects.filter(slug="about").exists()
+
+    # Tagged article must carry the seeded tag
+    tagged = ArticlePage.objects.get(slug="e2e-tagged-article")
+    assert tagged.tags.filter(slug="ai-tools").exists()
+
+    # No-comments article must have comments disabled
+    no_comments = ArticlePage.objects.get(slug="e2e-no-comments")
+    assert no_comments.comments_enabled is False
+
+
+@pytest.mark.django_db
+def test_seed_e2e_content_is_idempotent():
+    """Running the command twice must not raise or create duplicates."""
+    call_command("seed_e2e_content")
+    call_command("seed_e2e_content")
+    assert ArticlePage.objects.filter(slug="nightly-playwright-journey").count() == 1