Fix comments UX regressions and HTMX/Turnstile behavior

- standardize comment and reply UI layout
- target replies with stable OOB container IDs
- remove stale empty-state on approved HTMX comments
- initialize Turnstile widgets after HTMX swaps
- add regression tests for empty-state, OOB targets, and reply form rerender

Refs #48

templates/comments/_comment_list.html

@@ -1,4 +1,4 @@
-<div id="comments-list" class="space-y-12 mb-16"
+<div id="comments-list" class="space-y-6 mb-8"
   hx-get="{% url 'comment_poll' article_id=page.id %}" hx-trigger="every 30s" hx-swap="innerHTML">
   {% for comment in approved_comments %}
     {% include "comments/_comment.html" with comment=comment page=page %}