feat(editor): extract chat runtime (#14937)

#### PR Dependency Tree


* **PR #14937** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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

* **New Features**
* Centralized AI event system and a runtime powering chat sessions and
actions.

* **Improvements**
* Chat UI (composer, messages, toolbar, tabs, panels) now syncs with
runtime snapshots for more consistent state.
* Improved session/tab lifecycle (create, fork, delete), context
embedding status, and history handling.
* More reliable send/stop/retry flows, better telemetry scoping, and
clearer upgrade/login/insert-template prompts.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/affine-cloud-copilot/e2e/utils/settings-panel-utils.ts

@@ -226,8 +226,8 @@ export class SettingsPanelUtils {
     timeout: number,
     status = 'synced'
   ) {
+    await cleanupWorkspace(page.url().split('/').slice(-2)[0] || '');
     await expect(async () => {
-      await cleanupWorkspace(page.url().split('/').slice(-2)[0] || '');
       await this.openSettingsPanel(page);
       const title = page.getByTestId('embedding-progress-title');
       // oxlint-disable-next-line prefer-dom-node-dataset