Draft ADR-0018 (Stage 2 runtime rig) and mark the remaining contract-bake items blocked

docs/npc-model-sourcing.md

@@ -198,6 +198,10 @@ deltoid + hand) — both are the gate's rejection conditions.
 contract proportions; the gate fails and Stage 2 (a 62-joint runtime ADR) is indicated. Do not
 start the 12-variant rebuild on the warped base.
 
+[ADR-0018](adr/0018-quaternius-stage2-runtime-rig.md) records the Stage 2 decision: adopt the
+Quaternius source proportions at runtime (option 1: keep the 13-core names with Quaternius rest
+positions; option 2: ship the 62-joint rig), pending the owner's choice.
+
 ## Contract mismatch
 
 The expensive part is the rig and proportions, not the mesh. The source has a