Drop the committed packwiz binary (built against glibc 2.34, incompatible
with the runner's node:20-bullseye / glibc 2.31). Instead fetch Go into
the image and 'go install github.com/packwiz/packwiz@latest' so it links
against the runner's glibc. Keeps the working inline git clone + tag-gated
release.
Replace actions/checkout, setup-go, upload-artifact with an inline git
clone and a committed packwiz binary (tools/packwiz), so the workflow
needs no outside network beyond the docker image pull and a clone from
the instance itself. Release step (tag-gated) unchanged.
