combine: move each tool into its target's frame

A Combine took its tools in their own component's coordinates and joined
them to a target kept in another component's: a root body joined into a
body of a component turned a quarter turn landed where the turn carries
its root coordinates (#3383, 2 shells and 17000 mm3 instead of one solid
of 16750). Each tool is now moved through its own placement and the
inverse of the target's (component placement, then body offset), as
state_in_frame places bodies, and a combine's cache key follows the
placements so moving a component recomputes it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/frames_tests.rs

@@ -370,3 +370,28 @@ fn an_explicit_sketch_plane_is_read_in_the_frame_asked_for() {
         assert!(e.contains(why), "{p}: {e}");
     }
 }
+
+/// #3383: a root body joined into a body of a component turned a quarter turn about X stays where
+/// it is in the world: the join overlaps the plate by 10 x 5 x 5 and is one solid. When the
+/// component moves on, the join follows where both bodies are placed.
+#[test]
+fn a_combine_tool_stays_where_it_is_placed() {
+    let mut s = Session::default();
+    run(&mut s, "component.create", json!({"name": "Part"}));
+    run(&mut s, "solid.box", json!({"length": 40, "width": 40, "height": 10, "corner": [-20, -20, 0], "body_name": "Plate"}));
+    run(&mut s, "component.activate", json!({"component": "root"}));
+    run(&mut s, "occurrence.move", json!({"occurrence": "Part:1", "axis": [1, 0, 0], "angle": "90 deg"}));
+    run(&mut s, "component.capture_position", json!({}));
+    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10, "corner": [-5, -5, -25], "operation": "new", "body_name": "Boss"}));
+    run(&mut s, "solid.combine", json!({"target": "Plate", "tools": ["Boss"]}));
+    let lumps = |s: &Session| s.model.state().body("Plate").map(|b| b.body.lumps().unwrap().len());
+    assert_eq!(lumps(&s), Some(1), "the boss overlaps the plate where it is shown");
+    assert!((volume(&mut s) - 16750.0).abs() < 1e-6, "{}", volume(&mut s));
+    let (lo, hi) = world_bbox(&s, "Plate");
+    assert!(near(lo, Vec3::new(-20.0, -10.0, -25.0)) && near(hi, Vec3::new(20.0, 5.0, 20.0)), "{lo:?} {hi:?}");
+    // Raised 10 mm, the plate (z -10..30) clears the boss (z -25..-15).
+    run(&mut s, "occurrence.move", json!({"occurrence": "Part:1", "translate": [0, 0, 10]}));
+    run(&mut s, "component.capture_position", json!({}));
+    assert_eq!(lumps(&s), Some(2), "the boss stays where it is in the world");
+    assert!((volume(&mut s) - 17000.0).abs() < 1e-6, "{}", volume(&mut s));
+}