feat: cleanup chat panel (#14259)

#### PR Dependency Tree


* **PR #14258**
  * **PR #14259** 👈

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

* **Refactor**
* Split AI initialization into separate editor, app, and shared
registries; removed legacy chat-panel and replaced it with a
component-based editor chat, updating wiring and public exports.
* Propagated server/subscription/model services into chat/playground
components and improved session lifecycle and UI composition.

* **Tests**
* Added tests for AI effect registration and chat session resolution;
extended DOM/test utilities and assertions.

* **Chores**
  * Added happy-dom for runtime and test environments.

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packages/frontend/core/src/modules/peek-view/view/ai-chat-block-peek-view/index.tsx

@@ -1,6 +1,7 @@
 import { toReactNode } from '@affine/component';
 import { AIChatBlockPeekViewTemplate } from '@affine/core/blocksuite/ai';
 import type { AIChatBlockModel } from '@affine/core/blocksuite/ai/blocks/ai-chat-block/model/ai-chat-model';
+import { registerAIAppEffects } from '@affine/core/blocksuite/ai/effects/app';
 import { useAIChatConfig } from '@affine/core/components/hooks/affine/use-ai-chat-config';
 import { useAISubscribe } from '@affine/core/components/hooks/affine/use-ai-subscribe';
 import {
@@ -15,6 +16,8 @@ import type { EditorHost } from '@blocksuite/affine/std';
 import { useFramework } from '@toeverything/infra';
 import { useMemo } from 'react';
 
+registerAIAppEffects();
+
 export type AIChatBlockPeekViewProps = {
   model: AIChatBlockModel;
   host: EditorHost;