Signal form .reset() does not clear Angular Material error styling

### Which @angular/* package(s) are the source of the bug?

core, forms

### Is this a regression?

No

### Description

When using Angular Material form fields (`mat-form-field`) with signal-based forms (`@angular/forms/signals`), resetting the form after submission causes the Material input to display error styling (red outline) even though the field should no longer be in a touched or dirty state.

After calling `signalForm().reset()` on submit, the field value is correctly reset to an empty string. However, the Material form field renders as invalid with error styling applied. According to Angular Material's documented behavior, error styling should only be shown when the control has been touched. Since `reset()` is expected to clear both the `touched` and `dirty` states, the field should return to its pristine, untouched appearance — without any validation error indicators.

### Please provide a link to a minimal reproduction of the bug

https://stackblitz.com/github/mihai3636/2026--angular-signal-form-material-bug?file=src%2Fapp%2Fapp.ts

### Please provide the exception or error you saw

```true
N/A
```

### Please provide the environment you discovered this bug in (run `ng version`)

```true
Angular CLI : 22.0.4
Angular : 22.0.4
Node.js : 26.1.0
Package Manager : npm 11.13.0
Operating System : win32 x64

┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/build │ 22.0.4 │ ^22.0.0 │
│ @angular/cdk │ 22.0.2 │ ^22.0.2 │
│ @angular/cli │ 22.0.4 │ ^22.0.0 │
│ @angular/common │ 22.0.4 │ ^22.0.0 │
│ @angular/compiler │ 22.0.4 │ ^22.0.0 │
│ @angular/compiler-cli │ 22.0.4 │ ^22.0.0 │
│ @angular/core │ 22.0.4 │ ^22.0.0 │
│ @angular/forms │ 22.0.4 │ ^22.0.0 │
│ @angular/material │ 22.0.2 │ ^22.0.2 │
│ @angular/platform-browser │ 22.0.4 │ ^22.0.0 │
│ @angular/router │ 22.0.4 │ ^22.0.0 │
│ rxjs │ 7.8.2 │ ~7.8.0 │
│ typescript │ 6.0.3 │ ~6.0.2 │
│ vitest │ 4.1.9 │ ^4.0.8 │
└───────────────────────────┴───────────────────┴───────────────────┘
```

### Anything else?

_No response_

Inizia con la riproduzione StackBlitz collegata e confronta signalForm().reset() con il comportamento di @angular/forms/signals e Angular Material mat-form-field. Traccia come reset aggiorna gli stati touched, dirty e di validazione; il lavoro è completato quando il valore viene reimpostato e il campo Material non mostra più lo stile di errore dopo l'invio.

Scritto dal modello di indicizzazione a partire dal testo della issue.