gateFlake judges the formatting check right after the lock moves, but the
fmt area runs last, so the new toolchain's formatting had not been applied
yet and the flake area dropped itself every run.
nixpkgs decides which prettier and gofumpt format the tree. A lock bump to
prettier 3.9.6 reformatted CHANGELOG.md, which no area had touched, and the
formatting check failed on a file the bot never edited.
Keeps the interlocked pins current and reports what it could not move.
Areas apply, gate and commit one at a time, so a dependency that breaks
the build costs one commit rather than the whole pull request.
Kristoffer Dalby