Add scene-chain option nodes

README.md

@@ -128,6 +128,16 @@ blocking, action, performance, camera, composition, and lighting layers. Use
 `SxCP Hardcore Branch Options`, then render both sides through
 `SxCP Scene Pair Output`.
 
+Each layer can stay light on the main chain and take optional side-node inputs:
+`SxCP Scene Layer Seed Options`, `SxCP Scene Cast Options`,
+`SxCP Scene Character Options`, `SxCP Scene Wardrobe Options`,
+`SxCP Scene Location Layout Options`, `SxCP Scene Set Dressing Options`,
+`SxCP Scene Blocking Options`, `SxCP Scene Action Options`,
+`SxCP Scene Performance Options`, `SxCP Scene Camera Options`,
+`SxCP Scene Composition Options`, `SxCP Scene Lighting Options`, and
+`SxCP Scene Branch Options`. These side nodes are chainable and only override
+the layer they are connected to.
+
 The current v2 output nodes intentionally reuse the existing builder,
 Insta/OF pair, and formatter metadata routes. This keeps old workflows working
 while giving new workflows a cleaner movie-scene structure.