Wondering whether this shouldn't actually be part of `release:safari`?  Do you need to sign a .safariextension if you just want to load a local dev build into your local Safari browser?

I guess that clarifies your recent question/suggestion of whether we shouldn't rename (or split) the current `build` tasks... — FF just compiles + builds/archives, Chrome does the same, only `build:safari` additionally tries to sign the extension to prepare it for a published release.