Make images in preview zoomable via pinch zoom

[Shinigami92]

On mobile/pwa it is sometimes hard to read content in an image
It should be possible to zoom the image via pinch zoom
The content in background should not be affected by that

[stackblitz]

Start a new pull request in StackBlitz Codeflow.

[sarajw]

Thanks for writing the issue, I find this a big problem for mobile use!

[BagelHero]

This was discussed by some users at issue #740 , they perhaps went unseen because the initial issue was slightly different. I agree with LarsFosdal and clarioncat's notes in there, for what that's worth.

[purcell]

Yes! It's super common to click on an image on mobile devices and then want to zoom and pan around, either to see details or read small text. The inability to do this has really been the only jarring thing I've encountered when using Elk.