feat: add extended animation encoding options

[heidi-alps]

Summary

• Add support for additional WebP animation encoding options (minimize_size, allow_mixed, loop_count, bgcolor, kmin/kmax)
• Add per-frame encoding configuration (lossless/quality per frame)
• Fix memory leaks in original encodeAnimation() function

Changes

New Animation Options

Option	Type	Description
minimize_size	boolean	Minimize output size (slower, like img2webp -min_size)
allow_mixed	boolean	Allow mixed lossy/lossless per frame
loop_count	number	Animation loop count (0 = infinite)
bgcolor	number	Background color (ARGB format)
kmin / kmax	number	Keyframe distance control

Per-Frame Configuration

Each frame can now have its own config with lossless and quality settings.

Usage Example

// Basic usage (backward compatible)
const webp = await encodeAnimation(100, 100, true, frames);

// With new options
const webp = await encodeAnimation(100, 100, true, frames, {
  minimize_size: true,
  allow_mixed: true,
  loop_count: 0,
});

// Per-frame settings
const framesWithConfig = [
  { data: frame1, duration: 100, config: { lossless: 1 } },
  { data: frame2, duration: 100, config: { lossless: 0, quality: 80 } },
];

Bug Fixes

• Added WebPPictureFree() calls to prevent memory leaks
• Added final NULL frame for correct duration handling
• Added WebPDataInit/Clear for proper cleanup

Test plan

• Existing tests pass (npm test)
• Manual testing with WebP Animator application
• Verified backward compatibility

🤖 Generated with Claude Code

[nieyuyao]

Could you add one API example to README?
Additionally, please revert the ci files and then push commits to trigger pipeline.

[heidi-alps]

Hi @nieyuyao,

I've addressed your feedback:

1. README updated - Added API examples for WebPAnimationOptions and WebPFrameConfig:

   • Example with global animation options (loop_count, bgcolor, minimize_size, etc.)
   • Example with per-frame quality configuration

2. CI files restored - Reverted the commit that removed workflow files.

The CI workflow has been triggered but requires your approval to run (since this is a fork PR).

Could you please approve the workflow run? Thank you!

[nieyuyao]

it would be better to specify a branch or tag here. @heidi-alps