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 <[email protected]>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

NOTICE

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+ModelCraft
+Copyright (c) 2026 ModelCraft contributors.
+Licensed under the MIT License or the Apache License, Version 2.0, at your option
+(LICENSE-MIT, LICENSE-APACHE).
+
+Third-party material
+
+Software dependencies are listed in Cargo.lock; their licences are in THIRD-PARTY-LICENSES.txt
+(`cargo xtask licences`). Geometry comes from SolidCraft (https://github.com/bherbruck/solidcraft,
+MIT OR Apache-2.0), which builds on the truck crates (https://github.com/ricosjp/truck, Apache-2.0,
+Copyright (c) RICOS Co. Ltd.), some with SolidCraft's modifications.
+
+Some code is adapted from sibling projects (SolidCraft, CADCraft), licensed MIT OR Apache-2.0;
+ATTRIBUTION.md lists the files.
+
+ModelCraft is an independent project and is not affiliated with, sponsored by or endorsed by
+Dassault Systèmes, MSC Software, Siemens Digital Industries Software or Ansys, Inc. Abaqus,
+Nastran, MSC Nastran, Simcenter Nastran and LS-DYNA are trademarks of their respective owners;
+they are used here only to describe file compatibility.