039d166972
Introduce the `layer-separation` generator (edit-elements node action) that splits a source image into a clean background layer, foreground image artifacts with bounding boxes, and editable text render data. - New layer_separation.go builds the separated result and artifacts - SubmitGeneratorTask routes layer-separation and move-object via a switch; standalone task completion + polling support - Extend artifact metadata with BBox and GeneratorName across the domain, API types, mapper, .api schema, and API.md - edit-elements gets a transparent manual-frame placeholder holding the separated foreground images and text layers beside the original Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>