Fix cropping for non-overlapping rectangles

[KiMomota]

Fixes #39

What changed

• Track the input rectangles that overlap the largest interior rectangle.
• Skip non-overlapping images while keeping image, mask, and ROI indices aligned.
• Treat edge-touching rectangles as non-overlapping.

Tests

• Added a regression test with a non-overlapping rectangle in the middle of the input list.
• python -m unittest tests.test_cropper passes.
• All pre-commit hooks pass for the changed files.
• The full suite ran locally; repeated runs showed two unrelated environment-sensitive failures in the existing performance timing check and a crop=False output-size tolerance check on Windows/OpenCV 5.