v0.4.1 — packaging hygiene (replaces 0.4.0)

Changed

• 0.4.1 replaces 0.4.0 (packaging hygiene). Shipped files referred to
  internal build tooling by name in comments and error messages; those
  references now read "the build toolchain". No functional change to any
  execution path.
• Model-registry annotation lookup: the optional per-component flag
  registry is now located via the NBX_MODEL_REGISTRY environment
  variable or a .nbx_registry pointer file (development setups); a
  configured-but-missing location raises instead of being silently
  ignored. Deployed installs without a registry are unchanged (documented
  defaults apply).