test: stabilize aggregate coverage waits

packages/typert/loader/tests/loader.spec.ts

@@ -172,9 +172,10 @@ describe('typert loader', () => {
     expect(ctx.typert.get('@fixture/late#Late')).toBeUndefined()
     await ctx.loader.create({ name: '@fixture/late' })
     await ctx.loader.await()
-    // The microtask flush and the dynamic import need a turn to settle.
-    await new Promise(resolve => setTimeout(resolve, 20))
-    expect(ctx.typert.get('@fixture/late#Late')).toBeDefined()
+    // Contributor import settles after Loader's own await boundary.
+    await vi.waitFor(() => {
+      expect(ctx.typert.get('@fixture/late#Late')).toBeDefined()
+    }, { timeout: 10_000 })
   })
 
   it('drops an in-flight manifest when the loader is disposed before import settles', LOADER_TEST_TIMEOUT, async () => {