Constrained Delaunay tetrahedralization (boundary recovery) and mesh.tet.generate (M2) (#29)

* predicates: LNC points, generic insphere and its perturbed form (Diazzi et al. 2023 §4.3)

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

* mesh: constrained Delaunay tetrahedralization (segment recovery with LNC Steiner points, gift-wrapping facet recovery, labelling)

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

* cdt: rounding repair, mesh.tet.generate, corpus CDT column; review cleanups (shared perturbation rule, one facet scan, cached coordinates, worklist segment recovery)

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

* mesh.tet.generate is ready in the catalogue; corpus table with the CDT column

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>

docs/architecture.md

@@ -61,8 +61,9 @@ Rules beyond the layer order:
    position.
 3. **Tetrahedral meshing.** Bowyer–Watson Delaunay on Shewchuk's adaptive predicates (symbolic
    perturbation for degeneracies), boundary recovery by the robust constrained Delaunay method of
-   Diazzi et al. 2023 (implicit Steiner points on indirect predicates, gift-wrapping fallback), so
-   every boundary triangle and its B-rep face tag survives. Then constrained Delaunay refinement to a
+   Diazzi et al. 2023 (implicit Steiner points on indirect predicates, gift-wrapping facet
+   recovery; `modelcraft-mesh::cdt`, command `mesh.tet.generate`), so every boundary triangle and
+   its B-rep face tag survives. Then constrained Delaunay refinement to a
    size field, ODT smoothing interleaved as in Tournois et al. 2009, and the Klingner–Shewchuk 2007
    improvement schedule against slivers.
 4. **Hexahedral meshing (the core).** Octree/grid dual all-hex first, the one family that meshes