The Dockerfile lint and build stages and Dockerfile.lint each carried
their own apk add list, a copy of what script/bootstrap installs. They
now copy script/, go.mod and go.sum and run script/bootstrap, so that
layer is reused until one of those changes. script/bootstrap gains a C
compiler check: the golang image has none, and cgo needs one.
The build adds -trimpath and -s -w; CGO_ENABLED=1 stays, as govips
links libvips. ARG VERSION moves to just above the build, so a new
version reruns neither script/bootstrap nor the tests.
Model: opus-5-5
clawbot