test(core): fix flaky focusNode test by using fake timers for rAF (#15865)

jsdom polyfills requestAnimationFrame as setTimeout(cb, 16). The
mountWithChart helper only awaited setTimeout(0) callbacks, so in CI
poll() (which calls capturePositions) had not yet fired when selectNode
was called, leaving storedPositions empty and causing focusNode to be
skipped — a non-deterministic race.

Replace the manual setTimeout(0) waits with vi.useFakeTimers() +
vi.runAllTimersAsync() so the rAF callback fires before assertions run.

Author: MilosPaunovic

ui/tests/unit/dependencies/composables/useDependencies.spec.ts

@@ -314,6 +314,7 @@ describe("useDependencies composable", () => {
             ],
             count: 3,
         });
+        vi.useFakeTimers();
         const wrapper = mount({
             template: "<div></div>",
             setup() {
@@ -323,13 +324,14 @@ describe("useDependencies composable", () => {
                 return {composable};
             },
         });
-        // Flush microtasks (promise resolution + Vue reactivity) then
-        // allow jsdom's setTimeout-based requestAnimationFrame to fire.
+        // Flush microtasks (promise resolution + Vue reactivity) so onMounted's
+        // async fetch resolves, then advance fake timers past jsdom's rAF polyfill
+        // (setTimeout 16 ms) so capturePositions() runs and storedPositions is populated.
         await nextTick();
         await nextTick();
-        await new Promise(resolve => setTimeout(resolve, 0));
-        await new Promise(resolve => setTimeout(resolve, 0));
+        await vi.runAllTimersAsync();
         await nextTick();
+        vi.useRealTimers();
         chartMock.setOption.mockClear();
         const {selectNode} = wrapper.vm.composable as ReturnType<typeof useDependencies>;
         return {selectNode, chartMock};