Epic 103: add reusable CPU vision kernels

[rsasaki0109]

Summary

• add stable caller-owned resize, gray, normalize, and CHW output APIs
• expose NumPy out= reuse and contiguous zero-copy input borrowing
• add safe large-image CHW parallel dispatch and VGA/1080p/4K OpenCV receipts

Validation

• cargo test -p spatialrust-vision --no-default-features --features full
• cargo bench -p spatialrust-vision --features full --no-run
• cargo test -p spatialrust-image
• cargo test -p spatialrust-platform
• cargo test -p spatialrust --features image-io,vision-full,platform --test vision_api_v1
• python -m pytest crates/spatialrust-py/tests -q
• python bench/opencv_comparison/run.py --suite vision-performance