fix(core): copilot tool restore (#13470)

Close [AI-410](https://linear.app/affine-design/issue/AI-410)

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

- New Features
  - None

- Bug Fixes
- Middle-click panning now reliably returns to the previously active
tool, including after using Copilot or frame navigation.
- Smoother, more responsive transition into panning to reduce accidental
selections.

- Refactor
- Simplified AI panel click-outside handling with no change to
user-visible behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/blocksuite/ai/widgets/ai-panel/ai-panel.ts

@@ -141,10 +141,7 @@ export class AffineAIPanelWidget extends WidgetComponent {
       !this.contains(e.target as Node)
     ) {
       this._clickOutside();
-      return true;
     }
-
-    return false;
   };
 
   private readonly _onKeyDown = (event: KeyboardEvent) => {