#1567 web: a long code line or a wide table scrolls inside its message instead of widening the page on phones

Description

## Summary

On a phone, a reply with a long code line or a wide table makes the whole chat wider than the screen. In iPhone Safari the page then zooms out and the layout breaks. With this change the code block and the table scroll sideways on their own, and the page keeps the screen's width.

## What changed

`serve/web/app.css` only:

- `.view` gets `min-width: 0`. It is a flex item, so by default it could not shrink below its widest content (a `pre` line does not wrap). That widened the page.
- `.st-bubble table` becomes a block with `max-width: 100%` and `overflow-x: auto`, so a wide table scrolls inside the message.

Nothing else changes. On a wide screen, where the content already fits, the layout is the same as before.

## Extra Notes

Tested on an iPhone in Safari with a real code reply. Also checked in a 375 px wide browser with a 100-character code line and a four-column table. Before the change the page was 752 px wide, after it 375 px, with the code and the table scrolling inside the message.