`go run build` cannot work — Go resolves a bare argument as an import
path, so it looks for a package named "build" in std. Wrap the existing
commands in make targets instead, which gives the `make build` /
`make check` ergonomics without changing the Go interface underneath.
The wrapper earns its keep beyond the aliasing: `make serve` builds and
previews dist/ in one step, `make test` runs exactly what CI runs, and
`make update` fails with a pointer to LOCAL_DEV.md when GITHUB_TOKEN is
unset rather than erroring out mid-run.
Cloudflare keeps calling `go run . -build` directly. Locally make is
convenience; in the build image it would be a dependency relied on for
no benefit.
