fix(derive): suggest valid component scopes

hemx-derive/tests/compile_fail.rs

@@ -223,6 +223,10 @@ mod handlers {
         stderr.contains("#[hemx::component(\"todos\")] does not match any generated handles"),
         "missing unknown component diagnostic in stderr:\n{stderr}"
     );
+    assert!(
+        stderr.contains("available generated components: admin"),
+        "unknown scope diagnostic must name the valid repair choice:\n{stderr}"
+    );
 }
 
 #[test]