kindsys: Move code ownership of CustomStructured to apps platform team (#60497)

kindsys: Separate code ownership of CustomStructured

.github/CODEOWNERS

@@ -241,6 +241,7 @@ lerna.json @grafana/frontend-ops
 embed.go @grafana/grafana-as-code
 /kinds/ @grafana/grafana-as-code
 /pkg/codegen @grafana/grafana-as-code
+/pkg/kindsys/kindcat_custom.cue @grafana/apps-platform-core
 /pkg/kindsys @grafana/grafana-as-code
 /pkg/kinds/*/*_gen.go @grafana/grafana-as-code
 /pkg/registry/corekind @grafana/grafana-as-code

pkg/kindsys/kindcat_custom.cue

@@ -0,0 +1,15 @@
+package kindsys
+
+// CustomStructured specifies the Kind category for plugin-defined arbitrary types.
+// Custom kinds have the same purpose as CoreStructured kinds, differing only in
+// that they are declared by external plugins rather than in Grafana core. As such,
+// this specification is kept closely aligned with the CoreStructured kind.
+//
+// Grafana provides Kubernetes apiserver-shaped APIs for interacting with custom kinds -
+// The same API patterns (and clients) used to interact with CustomResources.
+#CustomStructured: {
+	#Structured
+
+	lineageIsGroup: false
+	...
+}

pkg/kindsys/kindcats.cue

@@ -120,14 +120,6 @@ _sharedKind: {
 	// - get summary
 }
 
-// TODO
-#CustomStructured: {
-	#Structured
-
-	lineageIsGroup: false
-	...
-}
-
 // TODO
 #CoreStructured: {
 	#Structured