select.refineEdge takes `edits`: the Select and Mask workspace's Quick
Selection, Brush, Lasso, Object Selection, Select Subject, Clear Selection
and Invert, applied in order to the starting selection (or layer mask)
before the edge is refined. Cancel discards them, OK is one history step,
and agents drive them over MCP and the control channel.
- engine/select_mask_edits.rs: parse (bounded, every bad field an Err)
and a pure apply/apply_one the workspace preview can share
- algo matting::brush_region: soft round brush coverage (hardness)
- ATN export reports steps with edits instead of dropping them
- "Edits" label in the 21 catalogs
Part of #7069 and #8148 (the workspace UI follows in a second PR).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
