fix: resolve review round 2, E2E failures, and mypy error

Review blocker A — form error swap and false success:
- Change HTMX contract so forms target their own container (outerHTML)
  instead of appending to #comments-list
- Use OOB swaps to append approved comments to the correct target
- Add success/error message display inside form templates
- Remove hx-on::after-request handlers (no longer needed)

Review blocker B — reply rendering shape:
- Create _reply.html partial with compact reply markup
- Approved replies via HTMX now use compact template + OOB swap
  into parent's .replies-container
- Reply form errors render inside reply form container

E2E test fixes:
- Update 4 failing tests to wait for inline HTMX messages instead
  of redirect-based URL assertions
- Add aria-label='Comment form errors' to form error display
- Rename test_reply_submission_redirects to
  test_reply_submission_shows_moderation_message

Mypy internal error workaround:
- Add mypy override for apps.comments.views (django-stubs triggers
  internal error on ORM annotate() chain with mypy 1.11.2)

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

templates/comments/_reply.html

@@ -0,0 +1,10 @@
+<article id="comment-{{ comment.id }}" class="mt-6 ml-8 bg-zinc-50 dark:bg-zinc-900 border border-zinc-200 dark:border-zinc-800 border-l-2 border-l-brand-cyan p-4">
+  <div class="flex items-center gap-3 mb-2">
+    <div class="w-7 h-7 bg-gradient-to-tr from-brand-pink to-brand-cyan shrink-0"></div>
+    <div>
+      <div class="font-display font-bold text-sm">{{ comment.author_name }}</div>
+      <div class="font-mono text-xs text-zinc-500">{{ comment.created_at|date:"M j, Y" }}</div>
+    </div>
+  </div>
+  <p class="text-zinc-700 dark:text-zinc-300 text-sm leading-relaxed">{{ comment.body }}</p>
+</article>