- ast-parser: read for_value= prop for sub-variations (was always null,
causing fallback to positional "subvariation N" label)
- StatusPoller: calculate progress from currently_rendered_notes /
notes_in_total; show remaining_time string from status.json
- ShapeEditor/EnvelopeEditor: pass { undo } through onChange so callers
can revert in-place mutations
- PaneFO: makeChangeHandler stashes undo from info arg; discardEdit
calls undo() before clearing pendingEdit; depends_on handler provides
its own undo for the inline node.dependsOn mutation
