Rectangular and circular sketch patterns stay linked to their source: editing the pattern's count, spacing or the source geometry updates the copies, and the copies keep their point and radius relations. Patterns are saved under format 20; older designs keep their independent copies.
Moves the per-feature geometry handling (transforms, face points, profile selections, point expressions) into one geometry walk in feature_geometry.rs, with a golden record of what each feature kind moves. sheet.perforate holds no world geometry and joins the no-op arm.
Part 2 of #876: one walk over the references a feature holds (the sketches it's built from, the features it names, the bodies it works on) replaces three hand-written matches, with a golden record covering every variant.
inputs_mut, inputs and expressions are now built on one exhaustive walk (walk_exprs / walk_exprs_mut) instead of two hand-written matches over FeatureKind. inputs() no longer clones the feature, plane chains are walked with the same nesting cap for inputs as for expressions, and a new variant without a walk arm does not compile. A golden record of every variant's expressions guards the walk.
CamWight