Replaces the per-attachment .md attach_file loop with a single
attach_note call per comment item: combined.md rendered to HTML via
rex.comments.render. Sibling .md files keep being written to disk
for non-Zotero corpus consumers.
Idempotency cache shifts from (item_key, filename) to a per-item
"Comment text" title check.
Migration of the 33,351 existing .md attachments lands in a
follow-up one-shot script.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2f6e2d452c