fix: resolve flaky sidebar test by awaiting deferred nav items

The test was racing against the async navigation loader. The waitFor
now retries until the sidebar link actually renders instead of passing
early when the route component text appears.

Author: IzumiSy

packages/core/src/components/sidebar/default-sidebar.test.tsx

@@ -129,16 +129,15 @@ describe("DefaultSidebar auto-generation", () => {
       </AppShell>,
     );
 
-    await waitFor(() => {
-      expect(screen.getAllByText("Overview").length).toBeGreaterThan(0);
+    const overviewLink = await waitFor(() => {
+      const sidebar = document.querySelector('[data-slot="sidebar"]')!;
+      const links = sidebar.querySelectorAll("a");
+      const link = Array.from(links).find((link) => link.textContent === "Overview");
+      expect(link).toBeDefined();
+      return link!;
     });
 
-    const sidebar = document.querySelector('[data-slot="sidebar"]')!;
-    const links = sidebar.querySelectorAll("a");
-    const overviewLink = Array.from(links).find((link) => link.textContent === "Overview");
-
-    expect(overviewLink).toBeDefined();
-    expect(overviewLink!.className).toContain("astw:bg-sidebar-accent");
+    expect(overviewLink.className).toContain("astw:bg-sidebar-accent");
   });
 
   it("excludes componentless resources from sidebar links", async () => {