Covers the DB-backed HTTP paths the async repo conversion touches — auth, users,
messages, attachments, conversations/groups, reactions, mentions, edit/delete,
polls, scheduled meetings (paginated), favorites, audit — asserting current API
shapes. Runs to completion with a pass/fail count and honours DB_BACKEND so it
doubles as the sqlite-vs-pg parity check at cutover. No WS/signaling (in-memory,
not the DB).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
