fix(lint,test): unblock CI on chore/fc-10-explore-sqllab-misc

Two failures from the latest commits on this branch:

1. oxlint no-use-before-define on DatasourceEditor.tsx — the
   isEditModeRef / onQueryFormatRef declarations sat after the
   componentDidMount useEffect that closes over them. JavaScript closes
   over the names at call time so it ran fine, but oxlint reads top-down
   and flags the order. Move the ref declarations and their sync useEffect
   ahead of the componentDidMount effect; lint clean and behavior
   identical.

2. CopyToClipboard.test.tsx used userEvent.keyboard('{enter}'), an API
   added in @testing-library/user-event v13.4. The pinned version in this
   repo is v12.8.3, so the call resolves to undefined and the test
   crashes with TypeError. Switch to fireEvent.keyDown(button, {key:
   'Enter'}), which is v12-compatible and directly exercises the
   component's onKeyDown handler we're testing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

superset-frontend/src/components/CopyToClipboard/CopyToClipboard.test.tsx

@@ -17,6 +17,7 @@
  * under the License.
  */
 import {
+  fireEvent,
   render,
   screen,
   userEvent,
@@ -59,7 +60,9 @@ test('non-element copyNode wrapper is keyboard-activatable', async () => {
   const button = screen.getByRole('button');
   expect(button).toHaveAttribute('tabIndex', '0');
   button.focus();
-  await userEvent.keyboard('{enter}');
+  // user-event v12 (pinned in this repo) doesn't expose .keyboard(); use
+  // fireEvent to dispatch the Enter keydown directly to the focused button.
+  fireEvent.keyDown(button, { key: 'Enter' });
   await waitFor(() => expect(onCopyEnd).toHaveBeenCalled());
 });
 

superset-frontend/src/components/Datasource/components/DatasourceEditor/DatasourceEditor.tsx

@@ -1360,6 +1360,14 @@ function DatasourceEditor({
     [],
   );
 
+  // Keep the refs read by the (one-shot) Mousetrap handler up to date.
+  const isEditModeRef = useRef(isEditMode);
+  const onQueryFormatRef = useRef(onQueryFormat);
+  useEffect(() => {
+    isEditModeRef.current = isEditMode;
+    onQueryFormatRef.current = onQueryFormat;
+  }, [isEditMode, onQueryFormat]);
+
   // componentDidMount
   useEffect(() => {
     isComponentMounted.current = true;
@@ -1394,14 +1402,6 @@ function DatasourceEditor({
     };
   }, []);
 
-  // Keep the refs read by the (one-shot) Mousetrap handler up to date.
-  const isEditModeRef = useRef(isEditMode);
-  const onQueryFormatRef = useRef(onQueryFormat);
-  useEffect(() => {
-    isEditModeRef.current = isEditMode;
-    onQueryFormatRef.current = onQueryFormat;
-  }, [isEditMode, onQueryFormat]);
-
   // componentDidUpdate for props.datasource changes
   // Only run when the props.datasource reference actually changes from parent
   useEffect(() => {