Prepare the modular part intake: inventory, extract, verify, join and the part contract

MEMORY.md

@@ -130,6 +130,12 @@ canonical implemented-features list in `docs/development-status.md`.
   gear library. The procedural library + MakeHuman head stay in the tree as the tested fallback
   (`build --source procedural`), not in the shipped roster. Silhouette variety is the known
   regression — three meshes for twelve roles — and the modular part library is the `0.9.10` fix.
+- **Modular part intake is a one-time manual download (2026-11-06, owner):** the upstream pack is a
+  Google Drive folder, so the owner downloads it once into the gitignored
+  `tmp/quaternius-intake/` and `tools/quaternius_parts.py` does the rest
+  (`inventory` → `extract` → `verify`). A part must be one skinned mesh on the 62-joint rig; a GLB
+  exported *without* an armature has no `JOINTS_0` and validates as bone-less, so `extract` keeps
+  the armature and `build` drops it again at join time.
 - **Hair variety is built in-project (2026-11-06):** the upstream modular pack is a Google Drive
   folder, so it cannot be fetched reproducibly; `QUATERNIUS_HAIR_PARTS` reshapes the one hair shell
   each base ships (`short` identity, `buzz` squash, `long` stretch, `bald` removal) and the role's