ModelCraft foundation: workspace, quality gates, FE model, command engine, geometry boundary

A pure-Rust CAE modeling workspace following the SolidCraft conventions:
- modelcraft-model: nodes and elements by label with hostile-input validation
- modelcraft-geometry: SolidCraft's kernel (pinned git dependency) behind our own API;
  tessellation into a face-tagged boundary surface for volume meshing
- modelcraft-engine: CommandSpec registry, Session::execute with rollback and panic guard,
  scripts and a journal
- modelcraft-cli: list commands, run scripts
- xtask: layers (only geometry may use solidcraft-*), assets, licences, tests, wasm, ci
- AGENTS.md, architecture, ADR 0001 (libraries and licences), roadmap, CI

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

docs/adr/0001-libraries.md

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+# ADR 0001: Libraries and licences
+
+Status: accepted (2026-10-13)
+
+## Context
+
+ModelCraft is MIT OR Apache-2.0. Everything it links must allow that, and the meshing and solver
+algorithms, where the obvious open-source implementations are GPL-family, must come from papers.
+
+## Decision
+
+**Geometry: SolidCraft's kernel**, as a git dependency pinned by rev
+(`solidcraft-kernel`, `solidcraft-geom`; MIT OR Apache-2.0, built on the Apache-2.0 truck
+crates). ModelCraft uses its B-rep bodies and its tessellation; it does not read CAD exchange
+files itself. Only `modelcraft-geometry` may depend on it.
+
+**Meshing: our own**, implemented from published papers (`docs/meshing/literature.md`).
+Robust predicates follow Shewchuk's adaptive-precision arithmetic (the paper; his reference
+`predicates.c` is public domain). A permissive crate may be adopted instead after review; record
+it here.
+
+**Linear algebra:** to be decided in the solver task, among permissively licensed pure-Rust
+crates (for example `faer`, MIT). Record the choice here.
+
+**Allowed:** MIT, BSD-2/3, Apache-2.0, ISC, Zlib, Unicode, MPL-2.0 (as an unmodified dependency),
+CC0 and public domain.
+
+**Rejected — never read, copy or link:**
+
+| Project | Licence | Would have offered |
+|---|---|---|
+| TetGen | AGPL-3.0 | constrained Delaunay tetrahedralization |
+| CGAL | GPL-3.0 / LGPL-3.0 | Delaunay, mesh generation |
+| Gmsh | GPL-2.0+ | tet and hex meshing |
+| Netgen | LGPL-2.1 | tet meshing |
+| CalculiX | GPL-2.0 | implicit solver, Abaqus-like input |
+| Code_Aster | GPL-3.0 | implicit solver |
+| OpenRadioss | AGPL-3.0 | explicit solver |
+| Elmer | GPL-2.0 / LGPL-2.1 | multiphysics solver |
+| deal.II, FreeFEM, Salome | LGPL | FE libraries, pre-processing |
+| OpenCASCADE | LGPL-2.1 | B-rep kernel |
+
+**Commercial products** (Abaqus, Nastran, LS-DYNA, LS-PrePost, HyperMesh, ANSA, Femap, Patran,
+ANSYS) are never run, scripted or used as a source of data. Deck formats come from the vendors'
+public reference manuals, described in our own words with our own examples.
+
+## Consequences
+
+- The tet and hex meshers are significant original work; the literature survey decides the
+  order and the methods.
+- SolidCraft and ModelCraft move together: bumping the pinned rev bumps the repeated
+  `[patch.crates-io]` entries in the same commit.