NumberField decrement converts negative to positive

### Provide a general summary of the issue here

When setting `signDisplay` to `"never"`, ``'s decrement button converts negative values to positive, resulting in an incorrect post-decrement value

### 🤔 Expected Behavior?

Negative values should remain negative

### 😯 Current Behavior

Negative values are converted to positive

### 💁 Possible Solution

_No response_

### 🔦 Context

_No response_

### 🖥️ Steps to Reproduce

https://stackblitz.com/edit/vitejs-vite-xxqht6jk?file=src%2FApp.jsx

```jsx
import { useState } from 'react';
import {
NumberField,
Label,
Group,
Input,
Button,
} from 'react-aria-components';

function App() {
const [showSign, setShowSign] = useState(true);
const [value, setValue] = useState(0);

return (
<>

---

Value: {value}

-

+



);
}

export default App;
```

To reproduce:

1. Set value to `0`
1. Check 'Show sign'
1. Decrement value twice
- Notice that value decrements in the negative direction correctly: `0` → `-1` → `-2`
1. Set value to `0`
1. Uncheck 'Show sign'
1. Decrement value twice
- Notice that value is not correctly decremented: `0` → `-1` → `0`

### Version

react-aria-components@1.12.1

### What browsers are you seeing the problem on?

Safari

### If other, please specify.

_No response_

### What operating system are you using?

macOS Tahoe 26.1

### 🧢 Your Company/Team

_No response_

### 🕷 Tracking Issue

_No response_