fix(editor): memory leak caused by missing unsubscription from autoUpdate (#13205)

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

## Summary by CodeRabbit

* **Bug Fixes**
* Improved resource cleanup for floating UI elements and popups to
prevent potential memory leaks and ensure proper disposal when
components are removed or updated.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/blocksuite/ai/components/copy-more.ts

@@ -160,6 +160,7 @@ export class ChatCopyMore extends WithDisposable(LitElement) {
           mainAxis: 0,
           crossAxis: -100,
         });
+        this.disposables.add(() => this._morePopper?.dispose());
       }
     }
   }

packages/frontend/core/src/blocksuite/ai/widgets/edgeless-copilot/index.ts

@@ -54,6 +54,8 @@ export class EdgelessCopilotWidget extends WidgetComponent<RootBlockModel> {
 
   private _selectionModelRect!: DOMRect;
 
+  private _autoUpdateCleanup: (() => void) | null = null;
+
   groups: AIItemGroupConfig[] = [];
 
   get gfx() {
@@ -145,7 +147,8 @@ export class EdgelessCopilotWidget extends WidgetComponent<RootBlockModel> {
 
     const originMaxHeight = window.getComputedStyle(panel).maxHeight;
 
-    autoUpdate(referenceElement, panel, () => {
+    this._autoUpdateCleanup?.();
+    this._autoUpdateCleanup = autoUpdate(referenceElement, panel, () => {
       computePosition(referenceElement, panel, {
         placement: 'bottom-start',
         middleware: [
@@ -267,6 +270,8 @@ export class EdgelessCopilotWidget extends WidgetComponent<RootBlockModel> {
         this._copilotPanel = null;
       })
     );
+
+    this._disposables.add(() => this._autoUpdateCleanup?.());
   }
 
   determineInsertionBounds(width = 800, height = 95) {