test(studio): assert stopPropagation prevents onSelect on remove click

Review proved the existing test didn't catch a broken stopPropagation
by temporarily removing it and confirming the suite still passed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packages/studio/src/components/editor/propertyPanelFlatTextSection.test.tsx

@@ -79,6 +79,10 @@ describe("FlatTextLayerList", () => {
     );
     act(() => removeButton?.dispatchEvent(new MouseEvent("click", { bubbles: true })));
     expect(onRemove).toHaveBeenCalledWith("a");
+    // stopPropagation on the remove button must prevent the row's own onClick
+    // from also firing onSelect for the removed field's key.
+    expect(onSelect).toHaveBeenCalledTimes(1);
+    expect(onSelect).not.toHaveBeenCalledWith("a");
     act(() => root.unmount());
   });
 });