geometry: defeature a design by suppressing its features, virtually when they cannot be

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

crates/geometry/src/lib.rs

@@ -18,6 +18,7 @@
 #![forbid(unsafe_code)]
 
 pub mod check;
+pub mod defeature;
 mod design;
 mod edges;
 pub mod face_split;