bug(Listbox): Can not select first option with Enter after calling .goToFirst() (@angular/aria)

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

_No response_

### Description

When calling `.goToFirst()` the first option is set active. But it is not possible to select it with _Enter_. If the user hits _arrow down_ one time you can select the first option. But my whole reason for calling `.goToFirst()` is so the user do not need arrows when first option is the one they want.

I suspect an underlying keyboard manager is not being synced when calling `.goToFirst()'

### Reproduction

StackBlitz link: https://stackblitz.com/edit/go-to-first-issue-angular-aria-wpcbw3sz?file=src%2FApp.ts
Steps to reproduce:
1. Load stackblitz
2. Hit enter
Hitting enter should trigger en alert with the text "Option 0", but it does not happen

### Expected Behavior

When calling `.goToFirst()` the first option is selected and hitting Enter on the keyboard will select it.

### Actual Behavior

Nothing happens when hitting Enter

### Environment

- Angular: 21.1.3
- CDK/Material: 21.1.3
- Browser(s): Edge, Firefox
- Operating System (e.g. Windows, macOS, Ubuntu): Windows, Macos

リンクされている StackBlitz の再現手順、特に src/App.ts から始め、.goToFirst() の後に Enter を押すシーケンスを再現してください。keyboard-manager の同期に関する疑いを調査し、最初のオプションに移動した後に Enter を押すと、Arrow Down を必要とせずに "Option 0" を含む alert が発生することを確認してください。

索引モデルが issue の本文から書いたものです。