engine: geometry.defeature takes features out of the design for meshing (#433)

Suppresses the SolidCraft features named (holes filled, fillets and chamfers back to
their sharp edges, bosses removed) and rebuilds the design; a feature that cannot be
suppressed alone is merged into its neighbour for meshing only. Kept in the model,
replayed on open, undoable; geometry.defeature.delete turns them back on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/engine/src/cmd/mod.rs

@@ -5,6 +5,7 @@ mod cells;
 mod contact;
 pub(crate) mod datum;
 pub(crate) mod deck;
+mod defeature;
 pub(crate) mod define;
 pub mod diagnostics;
 mod edit;
@@ -79,6 +80,8 @@ pub static ALL: &[CommandSpec] = &[
     virtual_faces::FACE_ABSORB,
     virtual_faces::FACE_SPLIT,
     virtual_faces::FACE_SPLIT_DELETE,
+    defeature::DEFEATURE,
+    defeature::DEFEATURE_DELETE,
     stitch::STITCH,
     stitch::STITCH_DELETE,
     mesh::NODE_ADD,