Consider limiting the max html width of a slider when slicing tensors

Thanks again for this library, it is a joy to use (especially with penzai's named arrays).

I have a small quality of life fix I corrected locally, and would suggest to backport upstream:
When slicing a tensor, the html length of the slider is currently calculated (in `arrayviz.js`) as:
```js
slider.style.width = `calc(max(40ch, ${size}px))`;
```
but this means that if that dimension along which you're slicing is high (in my example it represents time for about ~25000 steps), you have to scroll laterally to interact with the bar. I suggest a maximum size for the bar, like:
```js
slider.style.width = `calc(min(500px, max(40ch, ${size}px)))`;
```
Thanks again!