bug(mat-chip-grid): impossible to navigate to the input using VoiceOver commands when there are chips selected

### 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 nesting input inside of the mat-chip-grid, it becomes inaccessible with the screenreader commands (when there are chips selected).

### Reproduction

StackBlitz link: https://stackblitz.com/run?file=src%2Fexample%2Fchips-input-example.html
Steps to reproduce:
1. Use material chips with input, where input is nested inside of mat-chip-grid.
2. Add at least one chip.
3. Start VoiceOver and focus the form field.
4. Navigate inside the form field using VoiceOver commands (e.g. VO-Right Arrow to move to the next item)

### Expected Behavior

It should be possible to focus the input element when pressing VO-Right Arrow inside the mat-chip-grid. Similar to how it is in chip-autocomplete example, when input is not inside the mat-chip-grid:
https://stackblitz.com/run?file=src%2Fexample%2Fchips-autocomplete-example.css

### Actual Behavior

Only chips and delete buttons can be focused using VoiceOver commands.

### Environment

- Angular: 19.0.5
- CDK/Material: 19.0.5
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): MacOS

Commencez par reproduire le problème dans l’exemple StackBlitz lié avec Angular Material 19.0.5 sur macOS et VoiceOver, en suivant les étapes indiquées après avoir ajouté un chip. Consultez les exemples mat-chip-grid et chip-autocomplete pour comparer le comportement du focus ; c’est terminé lorsque VO-Right Arrow peut atteindre l’input imbriqué tandis que les chips restent sélectionnés.

Rédigé par le modèle d'indexation à partir du texte de l'issue.