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_

从链接的 StackBlitz reprodu​​ction 开始，并将 signalForm().reset() 与 @angular/forms/signals 和 Angular Material mat-form-field 的行为进行比较。跟踪 reset 如何更新 touched、dirty 和验证状态；完成的标准是值被重置，并且提交后 Material 字段不再显示错误样式。

由索引模型根据 Issue 内容生成。