Avoid flicker when checkpoint toolbar appears on request

[roblourens]

When scrolling to a request row in the chat list, the checkpoint toolbar (and other MenuWorkbenchToolBar instances) would not populate their actions until after the debounced menu change event fired (~50-100ms after context keys were set in renderElement). This caused a visible height jump as the toolbar went from empty to populated.

Changes

src/vs/platform/actions/browser/toolbar.ts

• Added a refresh() method to MenuWorkbenchToolBar that forces an immediate synchronous re-evaluation of menu actions
• Promoted the local updateToolbar closure to a private _updateToolbar() method, storing the necessary state (_menu, _menuOptions, _toolbarOptions, _container) as class fields

src/vs/workbench/contrib/chat/browser/widget/chatListRenderer.ts

• After setting context keys during renderChatTreeItem, call refresh() on all four toolbars (title, footer, checkpoint, checkpoint restore) to force synchronous action evaluation
• Removed the previous eventDebounceDelay: 0 workaround from the footer toolbar

(Written by Copilot)

cc @jrieken

[Copilot]

Pull request overview

This PR addresses a UI flicker/height jump in the chat list by ensuring MenuWorkbenchToolBar instances can synchronously populate actions immediately after context keys are updated, instead of waiting for the menu’s debounced change event.

Changes:

• Added MenuWorkbenchToolBar.refresh() to force an immediate synchronous re-evaluation of menu actions.
• Refactored MenuWorkbenchToolBar’s internal update closure into a private method with stored state.
• Updated the chat list renderer to call refresh() on relevant toolbars after setting context keys, and removed the prior eventDebounceDelay: 0 workaround on the footer toolbar.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/vs/platform/actions/browser/toolbar.ts	Adds a synchronous refresh() API and refactors menu-driven toolbar update logic into a method.
src/vs/workbench/contrib/chat/browser/widget/chatListRenderer.ts	Forces immediate toolbar action evaluation after context key updates to avoid visible layout shifts.