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>

e2e/test_comments.py

@@ -0,0 +1,53 @@
+"""E2E tests for the comment submission flow."""
+
+from __future__ import annotations
+
+import pytest
+from playwright.sync_api import Page, expect
+
+ARTICLE_SLUG = "nightly-playwright-journey"
+
+
+def _go_to_article(page: Page, base_url: str) -> None:
+    page.goto(f"{base_url}/articles/{ARTICLE_SLUG}/", wait_until="networkidle")
+
+
+@pytest.mark.e2e
+def test_valid_comment_submission_redirects(page: Page, base_url: str) -> None:
+    _go_to_article(page, base_url)
+
+    # Fill the main comment form (not a reply form)
+    form = page.locator("form[action]").filter(has=page.get_by_role("button", name="Post comment"))
+    form.locator('input[name="author_name"]').fill("E2E Tester")
+    form.locator('input[name="author_email"]').fill("e2e@example.com")
+    form.locator('textarea[name="body"]').fill("This is a test comment from Playwright.")
+    form.get_by_role("button", name="Post comment").click()
+
+    # Successful submission redirects back to the article with ?commented=1
+    page.wait_for_url(lambda url: "commented=1" in url, timeout=10_000)
+    assert "commented=1" in page.url
+
+
+@pytest.mark.e2e
+def test_empty_body_shows_form_errors(page: Page, base_url: str) -> None:
+    _go_to_article(page, base_url)
+
+    form = page.locator("form[action]").filter(has=page.get_by_role("button", name="Post comment"))
+    form.locator('input[name="author_name"]').fill("E2E Tester")
+    form.locator('input[name="author_email"]').fill("e2e@example.com")
+    form.locator('textarea[name="body"]').fill("   ")  # whitespace-only body
+    form.get_by_role("button", name="Post comment").click()
+    page.wait_for_load_state("networkidle")
+
+    # The page re-renders with the error summary visible
+    expect(page.locator('[aria-label="Comment form errors"]')).to_be_visible()
+    # URL must NOT have ?commented=1 — form was not accepted
+    assert "commented=1" not in page.url
+
+
+@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")
+    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)