04f719ba

By: Michael Lynch <git@mtlynch.io>

Remove comments from media pages (m7-10)

Replace the provisional 501 response with real comment deletion. A comment's
author, or any owner, can delete it; the handler rejects other users with 403
and reports 404 for an unknown comment. This completes Milestone 7: users can
add, edit, and delete comments and emoji reactions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>