Add NumPy and OpenCV image array support

[DeltaRule]

Summary

• Accept uint8 NumPy-compatible arrays directly.
• Support grayscale, RGB/BGR, and RGBA/BGRA images.
• Handle non-contiguous arrays safely.
• Preserve existing path and Pillow image support.
• Add type hints and OpenCV usage documentation.
• Keep NumPy and OpenCV as test-only dependencies.
• Test every existing barcode asset using OpenCV grayscale, color, and unchanged loading modes.

Verification

• Built the extension in release mode with Maturin.
• All 67 Python tests pass.
• 60 OpenCV asset/mode combinations are covered.