Remove comments heading and empty state

Drop the "Comments" section title (including the count) and the
"no comments yet" placeholder — the comment list now starts directly
with skeletons or comments followed by the form. The comments.none key
stays for the sidebar; comments.title is removed from both locales.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

i18n/locales/en.json

@@ -98,7 +98,6 @@
     "removePeriod": "Remove time range filter"
   },
   "comments": {
-    "title": "Comments",
     "none": "No comments yet.",
     "loading": "Loading comments…",
     "placeholder": "Write a comment… {'@'} to mention, drop files here",