Extract Insta pair row creation

docs/prompt-architecture-improvement-plan.md

@@ -144,17 +144,18 @@ Owner today: `build_insta_of_pair`.
 
 Keep here:
 
-- soft/hard row creation;
 - continuity policy;
 - softcore cast policy;
 
 Improve later:
 
-- split pair assembly into small functions by phase:
-  `build_soft_row`, `build_hard_row`.
+- split remaining pair cast/descriptor policy out of `build_insta_of_pair`.
 
 Already isolated:
 
+- soft/hard row creation lives in `pair_rows.py`, including softcore expression
+  override resolution, Woman A slot context application, soft outfit/pose
+  overrides, POV row fields, and hardcore row creation.
 - pair-level camera routing lives in `pair_camera.py`, including soft/hard
   camera config selection, same-as-softcore mode, camera-detail override,
   same-room hard scene continuity, camera-aware composition mutation, POV camera