18999157

By: Michael Lynch <git@mtlynch.io>

Persist comments from the media page (m7-6)

Replace the provisional 501 response with real comment persistence. Any
signed-in user can post a comment, which appears immediately and survives
reloads; empty or HTML-tag comments are rejected with a 400.

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