Animated GIF Encoding with Partial Frames and Transparency
Fixed animated GIF encoding to properly handle partial frames (frames smaller than canvas at offset positions).
Changes:
- Frame positions (
left,top) are now correctly preserved - Frame dimensions use actual frame size instead of canvas size
- Transparency is properly handled in partial frames
- Disposal methods (
none,background,previous) are preserved on round-trip
Backward Compatible - No breaking changes. Frame metadata is optional with sensible defaults.