fix: focus input editor when attachment zone is clicked (microsoft#242105)

Author: joyceerhl

src/vs/workbench/contrib/chat/browser/chatInputPart.ts

@@ -842,6 +842,7 @@ export class ChatInputPart extends Disposable implements IHistoryNavigationWidge
 		const hoverDelegate = this._register(createInstantHoverDelegate());
 
 		this._register(dom.addStandardDisposableListener(toolbarsContainer, dom.EventType.CLICK, e => this.inputEditor.focus()));
+		this._register(dom.addStandardDisposableListener(this.attachmentsContainer, dom.EventType.CLICK, e => this.inputEditor.focus()));
 		this.inputActionsToolbar = this._register(this.instantiationService.createInstance(MenuWorkbenchToolBar, toolbarsContainer, MenuId.ChatInput, {
 			telemetrySource: this.options.menus.telemetrySource,
 			menuOptions: { shouldForwardArgs: true },