Kernel: pole-free six-patch spheres; vendored truck-shapeops with robust meshing and nearest-parameter loop projection (sphere and box booleans work); least-squares sphere classification

Oracle: 25/29 (14 and 15 now match Fusion).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

vendor/README.md

@@ -0,0 +1,15 @@
+# Vendored third-party crates
+
+Copies of third-party crates that SolveCraft builds with local fixes, wired in with
+`[patch.crates-io]` in the workspace `Cargo.toml`. They keep their own licence; changed lines
+are marked `SolveCraft:` in the source.
+
+## truck-shapeops 0.4.0 (Apache-2.0, © RICOS Co. Ltd., https://github.com/ricosjp/truck)
+
+Changes:
+- `transversal/integrate/mod.rs`: mesh both shells with `robust_triangulation` (faces made by
+  earlier booleans have boundaries that lie on their surface only within tolerance).
+- `transversal/divide_face/mod.rs`: when projecting a loop onto a face's surface, fall back to
+  the nearest parameter when the exact search fails (intersection curves are approximations).
+- `lib.rs`: `tr!` reports where an operation gives up when `SHAPEOPS_TRACE` is set; compiler
+  warnings no longer fail the build.