engine: geometry.check reports what is small against the element size

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

crates/engine/src/cmd/mod.rs

@@ -51,6 +51,7 @@ pub static ALL: &[CommandSpec] = &[
     geometry::BODIES,
     geometry::FEATURES,
     geometry::CENTRE,
+    geometry::CHECK,
     geometry::TESSELLATE,
     geometry::IMPORT_MESH,
     datum::DATUM_PLANE,