Kernel tests: the chamfer on a tangent wall junction is measured on meshes fine enough

chamfer_the_top_lip_at_a_tangent_wall_junction measured the removed volume as the difference of
two meshes at chord 0.0005. The display planner meshes the two bodies differently, so their
chord errors no longer cancel as truck's meshes did: 37.404, 37.672, 37.761 and 37.759 mm³ at
chords 0.002, 0.0005, 0.0001 and 0.00003, converging on the expected 37.762 (the chamfer as the
chord between the contact lines of a 2 mm ball, integrated exactly). SMLib's chamfer is that
one; the test measures at chord 0.0001.

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

crates/kernel/tests/chamfer_curved_holder.rs

@@ -59,7 +59,12 @@ fn chamfer_the_top_lip_at_a_tangent_wall_junction() {
     assert_eq!(made.crossed_face_loops().unwrap(), 0);
     let history = made.history().expect("the chamfer retains exact face provenance");
     assert!(history.faces.iter().any(|f| f.origins.iter().any(|o| matches!(o, solidcraft_kernel::history::FaceOrigin::Edge { operand: 0, .. }))));
-    let mesh = |body: &Body| body.mesh(&solidcraft_kernel::MeshTolerance::chord(0.0005)).unwrap();
+    // Fine enough that the meshes' chord error is below the tolerance: the removed volume
+    // measured on meshes is 37.404 at chord 0.002, 37.672 at 0.0005, 37.761 at 0.0001 and 37.759
+    // at 0.00003, converged on the expected 37.762 (the chamfer as the chord between the contacts
+    // of a 2 mm ball). The planner's meshes of the two bodies differ, so their chord errors no
+    // longer cancel as truck's did.
+    let mesh = |body: &Body| body.mesh(&solidcraft_kernel::MeshTolerance::chord(0.0001)).unwrap();
     let before = mesh(&body).measure().volume;
     let after = mesh(&made);
     let removed = before - after.measure().volume;