feat: stabilize face attachments and closed spline workflows

crates/engine/src/frames_tests.rs

@@ -75,8 +75,9 @@ fn world_picks_map_into_the_component() {
     // The edge along X at the top front: world (65, 0, 10).
     run(&mut s, "solid.fillet", json!({"edges": [[65, 0, 10]], "radius": 2}));
     assert!(volume(&mut s) < v0 - 1.0, "the fillet cut material");
-    // A sketch on the moved top face sits at world z = 10 over the moved block.
-    run(&mut s, "sketch.create", json!({"plane": {"face": [70, 10, 10]}, "name": "Pad"}));
+    // The modified face has no certified lineage; explicitly freeze its picked plane.
+    // Its world pick still maps into the moved component exactly once.
+    run(&mut s, "sketch.create", json!({"plane": {"face": [70, 10, 10],"fixed":true}, "name": "Pad"}));
     run(&mut s, "sketch.circle.center", json!({"center": [20, 10], "radius": 2, "id": "PadCircle"}));
     let sketch = run(&mut s, "sketch.inspect", json!({"sketch": "Pad"}));
     let center = sketch["curves"].as_array().unwrap().iter().find(|c| c["id"] == "PadCircle").unwrap()["center"].as_str().unwrap().to_string();