Less stack-centric and location-centric model.

docs/stacks/react-vite.md

@@ -1,5 +1,12 @@
 # Web Frontends in Castle
 
+> **This is a stack — creation-time guidance for writing _new_ frontends.**
+> A stack is a template + conventions, not a runtime requirement. `castle create
+> --stack react-vite` scaffolds from it and seeds the program's default dev-verb
+> commands. An existing frontend adopted with `castle add` doesn't need this
+> stack — it declares its own `commands:`. See @docs/component-registry.md for
+> `commands:`, `stack:` (optional), and `repo:`.
+
 How to build, serve, and manage web frontends as castle components.
 
 ## Stack