- Note that tests now exist and run with uv run pytest. - Add SAM21 to the upstream services table. - Add sam21() to the _deps factory list. - Add a convention bullet about the SAM21 vs bbox frame asymmetry so future contributors don't add nuwa_to_cv_frame to the SAM21 branch. - Move 'import httpx' into the third-party imports block. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>