- Remove the weaker shadowing copies of the two T9 tests so the stronger
originals (which seed an engineer and assert eng.id in target_user_ids,
plus proposal_type/match_keywords) actually run.
- _resolve_recipients: treat an explicit empty target_user_ids as 'no
recipients' instead of falling back to the default owner/admin set.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>