feat: Support 10-bit YUV, and properly handle colorspaces (YCbCr transform matrix)

[mrousavy]

We had support for 10-bit YUV, but it rendered wrong colors (yellow/purple-ish pixels).

This PR fixes this by actually getting the color transform matrix from the buffer (which is stored as kCVImageBufferYCbCrMatrixKey), which tells us the Skia Color Space to use (SkYUVColorSpace);

• Rec709 (full or limited)
• Rec601 (limited) <- super rare
• BT2020 8-bit (full or limited)
• BT2020 10-bit (full or limited)
• JPEG full <- rare
• SMPTE240 (full or limited) <- super duper rare

This is now safe, since before we just kinda assumed colorspace based on format, now we actually know the transform function.

Before

YUV 4:2:0 8-bit	YUV 4:2:0 10-bit	YUV 4:2:2 10-bit

After

YUV 4:2:0 8-bit	YUV 4:2:0 10-bit	YUV 4:2:2 10-bit

[Copilot]

Pull request overview

This pull request adds proper support for 10-bit YUV video formats and implements correct colorspace handling by reading the YCbCr transform matrix from CVPixelBuffer metadata. Previously, the code made assumptions about colorspace based solely on pixel format, which resulted in incorrect colors (yellow/purple-ish pixels) for 10-bit YUV content.

Changes:

• Refactored colorspace detection to read the actual YCbCr matrix from CVPixelBuffer attachments (kCVImageBufferYCbCrMatrixKey)
• Added support for 422 and 444 chroma subsampling variants (8-bit and 10-bit)
• Improved Metal pixel format detection with explicit format handling instead of heuristics
• Enhanced validation and error messages for plane index bounds checking

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/skia/apple/SkiaCVPixelBufferUtils.h	Updated imports from CoreMedia to CoreVideo, changed getColorspace to accept CVPixelBufferRef instead of OSType, added helper method signatures
packages/skia/apple/SkiaCVPixelBufferUtils.mm	Implemented colorspace matrix reading from buffer metadata, added 422/444 format support, refactored Metal pixel format detection with explicit handling, improved validation

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