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_home.py

@@ -37,12 +37,11 @@ def test_theme_toggle_adds_dark_class(page: Page, base_url: str) -> None:
 
 
 @pytest.mark.e2e
-def test_newsletter_form_in_nav(page: Page, base_url: str) -> None:
+def test_nav_subscribe_cta_present(page: Page, base_url: str) -> None:
     page.goto(f"{base_url}/", wait_until="networkidle")
-    # The nav contains a newsletter form with an email input
     nav = page.locator("nav")
-    expect(nav.locator('input[type="email"]')).to_be_visible()
-    expect(nav.get_by_role("button", name="Subscribe")).to_be_visible()
+    # Nav has a Subscribe CTA link (not a form — wireframe spec)
+    expect(nav.get_by_role("link", name="Subscribe")).to_be_visible()
 
 
 @pytest.mark.e2e