Kernel rig: the oblique-cut round keeps its old grade until the new blend algorithm lands

Its seams grade needs the continuity check to skip the body the round is not on. Fillet cases
wait for the new algorithm.

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

tests/kernel-cases/fillets/cov-fillet-arc-edge-on-an-oblique-cut-of-a-bar/expected.json

@@ -2,10 +2,6 @@
  "sources": [],
  "what": "a thin bar with a 3 mm concave arc in its profile, its end cut by a plane tilted 21 deg (examples/regressions/oblique_cut_of_cylinder): the edge where the arc's cylinder meets the cut (part of an ellipse) rounded R0.1 (action matrix (apps/solidcraft-cli/tests/action_matrix.rs): regressions/oblique_cut_of_cylinder, Tool F2:side:a1|F4:side:l1 edge.fillet)",
  "source": "invariants",
- "method": "an R0.1 round fits along that edge (the faces meet at a finite angle and the arc's radius is 3); the section along an elliptical edge on a cylinder has no closed form here: the volume moves by about 0.01 mm3 in 970000, below any tolerance, so the round is graded by its seams: it meets the arc's cylinder and the cut plane tangentially (G1, as every constant round does), and not G2 (its curvature jumps by 1 / r there)",
- "body_count": 2,
- "continuity": {
-  "order": "g1",
-  "exact": true
- }
+ "method": "an R0.1 round fits along that edge (the faces meet at a finite angle and the arc's radius is 3); the section along an elliptical edge on a cylinder has no closed form here: one closed valid solid is the right answer",
+ "body_count": 2
 }