style: apply cargo fmt across workspace (as on main)

Formats the branch the way main's 9cf9ff2 did, so merging main only
conflicts where the code itself differs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013RyGiMXcsf9HTKfqDxaQGt

tests/parametric_constraints_solve.rs

@@ -737,9 +737,9 @@ fn midpoint_constraint_pulls_a_point_onto_a_lines_midpoint() {
 fn midpoint_constraint_supports_a_point_entity() {
     let mut scene = Scene::new();
     let base = add_line(&mut scene, 0.0, 0.0, 10.0, 6.0);
-    let point = scene.add_entity(EntityType::Point(codec::entities::Point::at(
-        Vector3::new(20.0, 20.0, 0.0),
-    )));
+    let point = scene.add_entity(EntityType::Point(codec::entities::Point::at(Vector3::new(
+        20.0, 20.0, 0.0,
+    ))));
     scene
         .parametric_constraint_set_mut(ParametricScope::ModelSpace)
         .add(