Development env. deployment

[donpui]

Due to decommission of AWS, we need to switch Development/Playground environment deployment to something like dev.winden.app on OVH.

This might require to have separate branch like dev, where all such changes first are merged there and then PRs created to main branch.

Long term solution could be, that each PR with be deployed separately with sort of prefix.

[meejah]

I would really like to avoid another branch. That's a lot of extra work. Could it be tag-based instead at least? (e.g. "whatever is in the playground" is based on some tag)

It's also probably not ideal to have it as a subdomain of the "real" application, as cookies and same-origin etc can "leak" unexpectedly.