Skip checks by default

[balsoft]

Running checks by default is annoying and makes iterative deployment a nuiscance. Disable checks by default, deprecate --skip-checks and add --check to enable checking.

[mkaito]

Seems potentially controversial. Add a setting in the flake spec?

[notgne2]

eh sure why not

[teto]

software should be designed for usage, not for development. I think the current default is better (just broken because it evaluates everything instead of just the current target).