Few-shot keypoint detection using pretrained feature models

Comparing the different featurizers on SPAIR:

Tests

Regression tests for the matcher and the crop geometry live in tests/. They use plain asserts, so they run without pytest installed:

python tests/test_matcher.py
python tests/test_crop_transform.py

(they are also plain pytest test functions, so uv add --dev pytest && uv run pytest works too.)