Fix the podspec issue for compatible header search path

FIX: _limitBytes type error

- Extract ICC profile from input color space using CGColorSpaceCopyICCData
- Use WebPMux API to embed ICCP chunk in WebP container with copy_data=1
- Automatically convert Simple Format (VP8) to Extended Format (VP8X)
- Add iOS 10+ availability check for CGColorSpaceCopyICCData
- Skip ICC profile when maxFileSize is set (size limit takes priority)
- Add comprehensive test (testWebPEncodingEmbedICCProfile)

This fixes color reproduction issues with wide color gamut images
(Display P3, Adobe RGB, etc.) on platforms that assume sRGB when
ICC profile is missing.

Fixes #119

- Add TestDisplayP3.png test image with Display P3 color space
- Add testWebPEncodingDisplayP3 to verify wide color gamut support
- Verify ICC profile embedding works correctly for Display P3 images (536 bytes)

This test demonstrates that ICC profile embedding preserves wide color
gamut information, preventing washed-out colors on Android and web browsers.

- Use copy_data=0 in WebPMuxSetImage and WebPMuxSetChunk to avoid unnecessary memory copies
- Ensure writer.mem and iccData remain valid until WebPMuxAssemble completes
- Release iccData only after WebPMuxAssemble finishes
- Clear writer memory as the final step

This reduces memory operations by 50% for images with ICC profiles.

Performance improvement:
- Before: Image data copied twice (SetImage copy + Assemble)
- After: Image data copied once (Assemble only)
- Benefit: ~50% reduction in memory operations for 1MB+ images

Add ICC Profile Embedding Support for WebP Encoding