Add ruff config to exclude alembic E402, SQLAlchemy F821, and pre-existing E501 line-length issues. Auto-fix 69 unused imports and 2 f-strings without placeholders. Manually fix 8 unused variables. Apply ruff format to 127 files. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Test cleanup deletes expired snapshots - Test snapshots within retention window are kept - Test deleted count is returned - Test empty table handled gracefully Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>