scripts/provision-gitea-runner.sh is a one-shot, idempotent host
setup for an act_runner LXC. It mounts persistent host volumes for
GOMODCACHE / GOCACHE / act-clones, pre-pulls the runner image,
pre-clones the common GitHub actions, installs golangci-lint, and
sets up a nightly cron to refresh the lot. Generic — no per-project
state.
With those persistent volumes in place, `cache: true` on
actions/setup-go becomes a net negative — the action keeps tar-ing /
un-tar-ing GOMODCACHE+GOCACHE through the Gitea cache backend on
every job, adding ~10s per job and overwriting the volume contents.
Drop it from all three jobs in ci.yml. Add a header comment block
explaining the runner-side expectations and the Go version / build
matrix / upload-artifact context for anyone reading later.
