[Feature]: Set zoom factor for web widgets

Feature description

Feature description

Web widgets always render at 100%, and there's no way to change it. Ctrl +/- doesn't work inside a web block, and zooming the Wave window scales the terminal blocks too.

I keep an internal dashboard in a web widget next to some terminals. It assumes a full-width browser, so at 100% it's mostly horizontal scrolling — around 80% would fit the block, but I can't set that without shrinking everything else.

A meta key like web:zoomfactor (float, default 1.0) would cover it:

"meta": {
    "view": "web",
    "url": "http://localhost:8080/",
    "web:zoomfactor": 0.8
}

Electron's setZoomFactor() takes 1.0 as 100%, so the config value reads naturally.

Happy to attempt a PR if this seems reasonable — looks like it'd follow the same shape as web:useragenttype (#2454).

Implementation Suggestion

No response

Anything else?

No response