Python:
- Save input image preview to ComfyUI temp dir after execution
- Use unique_id to generate stable filename per node instance
- Return UI dict with preview filename for frontend consumption
JS:
- Listen for onExecuted to receive preview image filename
- Load actual image from ComfyUI /view API
- Draw image centered at transforms origin — all transforms
(scale, rotation, flip, offset) apply naturally to the image
- Fall back to checkerboard grid when no preview loaded yet
- Fixed corner marker drawing bug