Delete Face (face.delete, and faces in the Delete selection): a timeline feature that removes faces and heals the gap from the neighbouring planes through kernel::delete_faces; a picked face brings the rest of its surface (both halves of a hole's wall); face picks are stored by persistent name; a face its neighbours can't close is refused with the kernel's reason

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/engine/src/lib.rs

@@ -425,6 +425,8 @@ impl Session {
     }
 }
 
+#[cfg(test)]
+mod delete_face_tests;
 #[cfg(test)]
 mod extent_tests;
 #[cfg(test)]