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>

templates/components/newsletter_form.html

@@ -3,7 +3,7 @@
   <input type="hidden" name="source" value="{{ source|default:'unknown' }}" />
   <input type="email" name="email" required placeholder="dev@example.com"
     class="w-full bg-transparent border border-zinc-300 dark:border-zinc-700 px-4 py-2 text-brand-dark dark:text-brand-light font-mono text-sm focus:outline-none focus:border-brand-pink transition-colors" />
-  <input type="text" name="honeypot" style="display:none" />
+  <input type="text" name="honeypot" hidden />
   <button type="submit"
     class="w-full bg-brand-dark text-brand-light dark:bg-brand-light dark:text-brand-dark font-display font-bold py-2 hover:bg-brand-pink dark:hover:bg-brand-pink hover:text-white transition-colors">
     {{ label|default:"Subscribe" }}