stack integration

GHCup can now install stack... but stack by default still manages GHC versions internally. Currently we print a post-install message:

Stack manages GHC versions internally by default. In order to make it use ghcup installed GHC versions have a look at the options 'system-ghc', 'compiler-check' and 'compiler': https://docs.haskellstack.org/en/stable/yaml_configuration/#system-ghc

Users will need to be aware of this. Maybe there's a more ergonomic way?

And even more important:

Additionally, you should upgrade stack only through ghcup.

This is because stack upgrades itself in-place, similar like ghcup does... this interferes with ghcups symlink story and how binaries are handled. It's not fatal, but will produce warnings and possibly unexpected results. I believe stack shouldn't do in-place updates unless explicitly told to. GHCup also doesn't do in-place updates... it defaults to ~/.ghcup/bin/ghcup.

Can we make this less wobbly?

And the last thing: if you want to use ghcups provided MSYS2, you need even more hoops in stack global config: skip-msys2, extra-path, extra-include-dirs, extra-lib-dirs

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information