Read from stdin and write to stdout

Is there a plan to support reading from stdin and writing to stdout? For instance in BunJS, I can do streaming:

```js
for await (let chunk of Bun.stdin.stream()) {}
```

```js
const writer = Bun.stdout.writer();
```

Start by reviewing LLRT's existing runtime I/O support against the requested BunJS entry points, Bun.stdin.stream() and Bun.stdout.writer(). Determine the intended streaming behavior and API surface, then verify that stdin can be consumed and stdout can be written incrementally as described.

Written by the indexing model from the issue text.