fix(editor): ci stability (#14704)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
* Improved Electron shutdown, diagnostics and tab teardown for more
reliable exits and forced cleanup on stubborn processes.
* **Tests**
* Added polling-based test helpers, stronger scroll/page readiness,
timeout-tolerant page selection, and async cleanup/worker teardown;
updated many tests to wait for UI/model updates and rendering frames.
* **Bug Fixes**
* Reduced flakiness by awaiting paragraph visibility, nested counts,
selection/navigation stability, tab counts, post-action renders, and
safer element interactions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/integration-test/src/__tests__/edgeless/layer.spec.ts

@@ -38,7 +38,7 @@ beforeEach(async () => {
 
   return async () => {
     await wait(100);
-    cleanup();
+    await cleanup();
   };
 });
 

blocksuite/integration-test/src/__tests__/edgeless/turbo-renderer.spec.ts

@@ -21,7 +21,7 @@ import {
 const FRAME = 16;
 
 describe('viewport turbo renderer', () => {
-  let cleanup: () => void;
+  let cleanup: () => Promise<void>;
 
   beforeEach(async () => {
     cleanup = await setupEditor('edgeless', [
@@ -34,7 +34,7 @@ describe('viewport turbo renderer', () => {
     return cleanup;
   });
 
-  afterEach(() => cleanup?.());
+  afterEach(async () => await cleanup?.());
 
   test('should access turbo renderer instance', async () => {
     const renderer = getRenderer();

blocksuite/integration-test/src/__tests__/utils/setup.ts

@@ -29,6 +29,7 @@ const viewManager = getTestViewManager();
 effects();
 
 const storeExtensions = storeManager.get('store');
+const painterWorkers = new Set<Worker>();
 
 export function getRenderer() {
   return editor.std.get(
@@ -108,6 +109,7 @@ export function createPainterWorker() {
       type: 'module',
     }
   );
+  painterWorkers.add(worker);
   return worker;
 }
 
@@ -141,19 +143,30 @@ export async function setupEditor(
 
   const appElement = await createEditor(collection, mode, extensions);
 
-  return () => {
+  return async () => {
+    await cleanup();
     appElement?.remove();
-    cleanup();
   };
 }
 
-export function cleanup() {
+export async function cleanup() {
   window.editor?.remove();
+  await window.editor?.updateComplete;
+  await new Promise<void>(resolve => requestAnimationFrame(() => resolve()));
+
+  for (const worker of painterWorkers) {
+    worker.terminate();
+  }
+  painterWorkers.clear();
 
   delete (window as any).collection;
 
   delete (window as any).editor;
 
+  delete (window as any).doc;
+
+  delete (window as any).renderer;
+
   delete (window as any).store;
 }