fix: nav/footer wireframe, honeypot CSP, explore topics, comment E2E coverage

- Replace nav inline newsletter form with Subscribe CTA link per wireframe
- Remove newsletter form from footer; add Connect section with social/RSS links
- Fix honeypot inputs using hidden attribute (inline style blocked by CSP)
- Add available_tags to HomePage.get_context for Explore Topics section
- Add data-comment-form attribute to main comment form for reliable locating
- Seed approved comment in E2E content for reply flow testing
- Expand test_comments.py: moderation message, not-immediately-visible,
  missing fields, reply form visible, reply submission
- Make COMMENT_RATE_LIMIT_PER_MINUTE configurable; set 100 in dev to prevent
  E2E test exhaustion; update rate limit unit test with override_settings
- Update newsletter/home E2E tests to reflect nav form removal
- Update unit test to assert no nav/footer newsletter forms

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

e2e/test_newsletter.py

@@ -7,7 +7,8 @@ from playwright.sync_api import Page, expect
 
 
 def _nav_newsletter_form(page: Page):
-    return page.locator("nav").locator("form[data-newsletter-form]")
+    """Return the newsletter form in the home page sidebar aside."""
+    return page.locator("aside").locator("form[data-newsletter-form]").first
 
 
 @pytest.mark.e2e
@@ -28,7 +29,7 @@ def test_subscribe_invalid_email_shows_error(page: Page, base_url: str) -> None:
     form = _nav_newsletter_form(page)
     # Disable the browser's native HTML5 email validation so the JS handler
     # fires and sends the bad value to the server (which returns 400).
-    page.evaluate("document.querySelector('nav form[data-newsletter-form]').setAttribute('novalidate', '')")
+    page.evaluate("document.querySelector('aside form[data-newsletter-form]').setAttribute('novalidate', '')")
     form.locator('input[type="email"]').fill("not-an-email")
     form.get_by_role("button", name="Subscribe").click()