Agents Window Codex smoke test times out waiting for focused Quick Input entry

## Failure

The **VSCode Smoke Tests (Electron)** failed in the **Agents Window (Codex) → Test Codex session** test while starting a new session.

Run: https://github.com/microsoft/vscode/actions/runs/33869381836/job/101011720827#step:31:206

```text
Error: Timeout: get elements '.quick-input-widget .quick-input-list .monaco-list-row.focused .quick-input-list-entry, .quick-input-widget .quick-input-list .monaco-list-row.focused .quick-input-list-row > .monaco-icon-label .label-name' after 20 seconds.
at Code.poll (/home/runner/work/vscode/vscode/test/automation/out/code.js:312:23)
at async Code.waitForElements (/home/runner/work/vscode/vscode/test/automation/out/code.js:253:16)
at async QuickInput.waitForQuickInputElement (/home/runner/work/vscode/vscode/test/automation/out/quickinput.js:29:32)
at async openCommandPalletteAndTypeCommand (/home/runner/work/vscode/vscode/test/automation/out/quickaccess.js:157:29)
at async QuickAccess.runCommand (/home/runner/work/vscode/vscode/test/automation/out/quickaccess.js:169:31)
at async AgentsWindow.startNewSession (/home/runner/work/vscode/vscode/test/automation/out/agentsWindow.js:71:9)
at async Context. (out/areas/agentsWindow/agentsWindow.test.js:301:13)
```

## Context

Observed on #334270. That PR only changes the Chat Customizations migration implementation, its unit tests, and its component fixture; it does not modify the Agents Window smoke test, Quick Input, or the automation helpers in this stack. The failure therefore appears unrelated to the PR changes.

No matching open issue was found using the failure/test names and Quick Input timeout terms.