Add the hair part library and give the roster three silhouettes

MEMORY.md

@@ -130,6 +130,11 @@ 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.
+- **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
+  existing `CHARACTERS[...]["hair"]` picks it. `bald` is restricted to bases whose skin closes the
+  skull. Outfit variety still needs the pack or new garments.
 - **No hats except the firefighter helmet (2026-11-06, owner):** the iconography is not worth the
   cost — a cap or hood on this head hides the face, and every hat needed a lift+scale hack to clear
   the 0.228 m hair shell. `ACCESSORIES` maps no role to `cap`/`hood`, the guard/vest per-character