feat(09-03): compile ordered Winter form schemas

- Strict config_form and fields documents keep source order and JSON scalar types
- Unknown keys, partials, path escape, and a mismatched modelClass fail activation with plugin context
- List-only controllers still activate when config_form.yaml is absent

cabana/contracts.go

@@ -78,6 +78,7 @@ type CompiledController struct {
 	PluginID   string
 	Controller pact.AdminController
 	List       *ListSchema
+	Form       *FormSchema
 }
 
 // Registry is the immutable controller map keyed by controller ID.