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

apps/comments/tests/test_v2.py

@@ -91,6 +91,7 @@ def test_htmx_post_returns_form_plus_oob_comment_when_approved(client, _article)
     # OOB swap appends the comment to #comments-list
     assert "hx-swap-oob" in content
     assert "Hello world" in content
+    assert 'id="comments-empty-state" hx-swap-oob="delete"' in content
     comment = Comment.objects.get()
     assert comment.is_approved is True
 
@@ -132,8 +133,8 @@ def test_htmx_reply_returns_oob_reply_when_approved(client, _article, approved_c
         )
     content = resp.content.decode()
     assert resp.status_code == 200
-    # OOB targets the sibling .replies-container of the parent comment article
-    assert f'hx-swap-oob="beforeend:#comment-{approved_comment.id} ~ .replies-container"' in content
+    # OOB targets a stable, explicit replies container for the parent comment.
+    assert f'hx-swap-oob="beforeend:#replies-for-{approved_comment.id}"' in content
     # Verify content is rendered (not empty due to context mismatch)
     assert "Replier" in content
     assert "Nice reply" in content
@@ -165,6 +166,30 @@ def test_htmx_error_with_tampered_parent_id_falls_back_to_main_form(client, _art
     assert b"comment-form-container" in resp.content
 
 
+@pytest.mark.django_db
+def test_htmx_invalid_reply_rerenders_reply_form_with_values(client, _article, approved_comment):
+    """Invalid reply keeps user input and returns the reply form container."""
+    cache.clear()
+    resp = client.post(
+        "/comments/post/",
+        {
+            "article_id": _article.id,
+            "parent_id": approved_comment.id,
+            "author_name": "Reply User",
+            "author_email": "reply@example.com",
+            "body": "   ",
+            "honeypot": "",
+        },
+        HTTP_HX_REQUEST="true",
+    )
+    assert resp.status_code == 200
+    content = resp.content.decode()
+    assert f'id="reply-form-container-{approved_comment.id}"' in content
+    assert "Comment form errors" in content
+    assert 'value="Reply User"' in content
+    assert "reply@example.com" in content
+
+
 # ── Turnstile Integration ────────────────────────────────────────────────────