Exact 3D Delaunay tetrahedralization (Bowyer–Watson, ghost hull, BRIO/Hilbert, verifier) (#14)

* mesh: exact Bowyer-Watson Delaunay tetrahedralization with ghost tets, BRIO/Hilbert order and a verifier

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mesh: Delaunay benchmark, hash-paired cavity faces, mesh.delaunay.points debug command

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mesh: simplify Delaunay helpers, share predicates and parsers, halve verifier work

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

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Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/mesh/src/predicates/mod.rs

@@ -104,6 +104,13 @@ impl std::ops::Mul for Sign {
     }
 }
 
+/// The sign of the volume `det[b − a, c − a, d − a]`: positive when `d` lies on the side of
+/// face `a, b, c`'s right-hand normal (the tet4 node order). It is [`orient3d`] negated.
+#[inline]
+pub fn tet_volume_sign(a: &Point3, b: &Point3, c: &Point3, d: &Point3) -> Sign {
+    -orient3d(a, b, c, d)
+}
+
 /// Whether `x` may be a point coordinate (see the module docs).
 #[inline]
 pub fn is_admissible(x: f64) -> bool {