[labs/ssr] Textarea value is not server side rendered

Nobody has claimed this yet.

### Which package(s) are affected?

SSR (@lit-labs/ssr)

### Description

When you try to SSR a textarea as ``, the value is not rendered. You get ``, instead of `John`.

On the other hand, an `` works as expected.

Example:

```js
class Foo extends LitElement {
constructor() {
super();
this.name = 'John';
}

render() {
return html`


${unsafeHTML(`${this.name}`)}
${staticHtml`${this.hasUpdated ? undefined : unsafeStatic(this.name)}`}
`;
}
}
customElements.define('my-foo', Foo);

function *renderPage() {
yield* render(html``);
}

new RenderResultReadable(renderPage())
```

This will render:

```html

John
John

```

### Reproduction

https://stackblitz.com/edit/lit-ssr-global-vvnu1gjw?file=src%2Fcomponents%2Fmy-foo.js

### Workaround

You can use:
```
${unsafeHTML(`${this.name}`)}
```
or

```
${staticHtml`${this.hasUpdated ? undefined : unsafeStatic(this.name)}`}
```

### Is this a regression?

No or unsure. This never worked, or I haven't tried before.

### Affected versions

3.3.0

### Browser/OS/Node environment

Node: 20+

The issue identifies @lit-labs/ssr and provides a StackBlitz reproduction; start by running that reproduction and tracing textarea handling in the SSR package. Done means the .value binding renders John, while the existing input behavior remains intact.

Written by the indexing model from the issue text.