docs: add engine assembly milestone concept and startup/shutdown playbook

docs: log 2026-04-18 alpha hardening and current HF deployment state

sec: harden modal worker, update deployment docs, and add pre-push safety checks

NaturalCAD: document Modal RCE and Auth vulnerabilities

NaturalCAD: Add LLM via HF Inference, GLB export, and update docs

NaturalCAD: final HF runtime attempt with pure pip stack

NaturalCAD: use strict conda-forge runtime for HF Space

NaturalCAD: simplify HF CAD runtime and add smoke test

NaturalCAD: expose Conda lib path for HF runtime

NaturalCAD: add hosted backend flow and Space fixes

Log libvtk missing shared object error for next session

Add HF Space build log documenting deployment issues

Add Hugging Face Space runtime guidance

Update NaturalCAD branding assets

Initial NaturalCAD MVP