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

TODO.md

@@ -770,12 +770,25 @@ regressing gear fit, budget or readability.
       place (`short` identity, `buzz` squashed toward the hairline, `long` stretched from the crown),
       and each role picks a style through the existing `CHARACTERS[...]["hair"]` field. The T-pose
       cache is keyed on the style. The roster now reads as three silhouettes instead of one.
-- [ ] **Outfit part library.** Unchanged ceiling: three outfit meshes for twelve roles. The upstream
-      modular pack is distributed as a Google Drive folder
-      (<https://drive.google.com/drive/folders/1USAAquX2JJWuA2m6zol0KUkFe3UkZ8zX>), which cannot be
-      fetched reproducibly by a script, so outfit variety needs either a manual intake of that pack
-      (with the CC0 licence + SHA-256 record) or new garments authored here. Decide which before
-      starting; a `bald` hair variant also needs a skull-covering crown on the `worker` base first.
+- [-] **Outfit part library (owner chose the one-time manual download).** The upstream modular pack is
+      a Google Drive folder (<https://drive.google.com/drive/folders/1USAAquX2JJWuA2m6zol0KUkFe3UkZ8zX>);
+      the owner downloads it once, everything after that is scripted. Steps:
+      1. download the pack and drop the archive (or its extracted folder) into
+         `tmp/quaternius-intake/` — that directory is gitignored;
+      2. `python3 tools/quaternius_parts.py inventory --dir tmp/quaternius-intake` — lists every GLB
+         with its meshes, triangles, bones and materials, so the usable parts are picked by
+         measurement instead of by filename;
+      3. `python3 tools/quaternius_parts.py extract --file <glb> --mesh <name> --out parts/<part>.glb`
+         writes one skinned part onto the 62-joint rig (the only accepted part shape);
+      4. `python3 tools/quaternius_parts.py verify --dir assets/models/blender_src/quaternius/parts`
+         records the SHA-256 of what was kept, then copy the accepted sources into
+         `assets/models/blender_src/quaternius/parts/` and add the rows to `CREDITS.md`;
+      5. assign parts per role in `CHARACTERS[...]["parts"]` and rebuild.
+      Nothing lands in `assets/` until step 5, and the pack itself is never committed.
+      Tooling is ready and proven: `inventory`/`extract`/`verify` work, and a scratch part joined
+      onto a base and exported cleanly before the pack arrived. The part contract is in
+      `assets/models/blender_src/quaternius/parts/README.md`. **Waiting on the owner's download.**
+      A `bald` hair variant also needs a skull-covering crown on the `worker` base first.
 - [ ] Bake per-slot albedo/normal/ORM maps and a per-slot atlas; the five slots currently share one
       whole-body UV set, which caps how much the cloth/pants tints can differ.