Invalid CSS when using Button wrapped with Popover and layer enabled

I use Next.js with `antd` and `@ant-design/nextjs-registry`:
```jsx

...

Smth

...

```

`AntdRegistry` internally wraps everything in `StyleProvider` and uses `extractStyle`. I've noticed that whenever Popover is wrapping a button on any page, `extractStyle` returns an invalid CSS. Here's an example:
```css
...

.css-var-R2cq.ant-popover {
--ant-popover-title-min-width: 177px;
--ant-popover-z-index-popup: 1030;
--ant-popover-arrow-shadow-width: 8.970562748477143px;
--ant-popover-arrow-path: path('M 0 8 A 4 4 0 0 0 2.82842712474619 6.82842712474619 L 6.585786437626905 3.0710678118654755 A 2 2 0 0 1 9.414213562373096 3.0710678118654755 L 13.17157287525381 6.82842712474619 A 4 4 0 0 0 16 8 Z');
--ant-popover-arrow-polygon: polygon(1.6568542494923806px 100%, 50% 1.6568542494923806px, 14.34314575050762px 100%, 1.6568542494923806px 100%);
--ant-popover-arrow-offset-horizontal: 12px;
--ant-popover-arrow-offset-vertical: 8px;
--ant-popover-inner-padding: 12px;
--ant-popover-title-margin-bottom: 8px;
--ant-popover-title-padding: 0px;
--ant-popover-title-border-bottom: none;
--ant-popover-inner-content-padding: 0px;
}

@layer antd@layer antd { /* Here's the problem it includes "@layer antd" twice */
.ant-progress { /* I have Progress component in a different place on that page */
font-family: var(--ant-font-family);
font-size: var(--ant-font-size);
box-sizing: border-box;
}

...
```

@Kiyumi-v reproduced the problem here https://github.com/ant-design/ant-design/issues/49853#issue-2406725596 (you might find more details about the issue there).

## Workaround
So far, the workaround is to copy the `AntdRegistry` component and modify the extracted styles not to include duplication of `@layer antd@layer antd` and replace with one `@layer antd`.
```diff
const AntdRegistry: FC = (props) => {
const [cache] = useState(() => createCache());
const inserted = useRef(false);

useServerInsertedHTML(() => {
let styleText = extractStyle(cache, { plain: true });

if (inserted.current) {
return null;
}
inserted.current = true;

+ styleText = styleText.replaceAll(/@layer antd@layer antd/g, '@layer antd');

return (

);
});

return <StyleProvider {...props} cache={cache} />;
};
```

Reproduce the issue with AntdRegistry, StyleProvider, Popover, Button, and layer enabled, then inspect the CSS returned by extractStyle. Trace how the @layer text is assembled and confirm that the generated output contains one @layer antd rather than the duplicated form; no specific test file is named in the issue.

Written by the indexing model from the issue text.