bug: IonPopover `keyboardClose={false}` does not prevent keyboard dismissal since ionic 8.7.4

### Prerequisites

- [x] I have read the [Contributing Guidelines](https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#creating-an-issue).
- [x] I agree to follow the [Code of Conduct](https://ionicframework.com/code-of-conduct).
- [x] I have searched for [existing issues](https://github.com/ionic-team/ionic-framework/issues) that already report this problem, without success.

### Ionic Framework Version

v8.x

### Current Behavior

When an `IonPopover` with `keyboardClose={false}` is presented while a text input is focused, the mobile keyboard closes immediately and focus is lost from the initial input.

### Expected Behavior

When an `IonPopover` with `keyboardClose={false}` is presented while a text input is focused, the mobile keyboard should be kept open and the focus should be held by the initial input.

### Steps to Reproduce

1. Go to: https://stackblitz.com/edit/vitejs-vite-w4vmmzwi. There is a minimal repo project there.
2. Type @ in the textarea. A popover with user suggestions should appear. On mobile, the keyboard and focus should stay open in the text area so you can type to filter — but it closes immediately due to the bug.
3. Test using Ionic 8.7.3. In that version it works as expected. You can edit the package.json for that.

### Code Reproduction URL

https://stackblitz.com/edit/vitejs-vite-w4vmmzwi

### Ionic Info

[WARN] You are not in an Ionic project directory. Project context may be missing.

Ionic:

Ionic CLI : 6.19.0

Utility:

cordova-res : not installed globally
native-run : not installed globally

System:

NodeJS : v22.21.1
npm : 11.7.0
OS : Linux 6.19

### Additional Information

Please mind that i am only using the Ionic Components [in an existing React Project](https://ionicframework.com/docs/react/adding-ionic-react-to-an-existing-react-project). I am not using Capacitor or any of the other native features.

Start by reproducing the issue from the linked StackBlitz project on mobile with Ionic 8.7.4, then compare the behavior with 8.7.3. Trace the IonPopover presentation and keyboard/focus handling, and verify that setting keyboardClose={false} keeps the original textarea focused and the keyboard open while suggestions appear.

索引モデルが issue の本文から書いたものです。