The host-safe unit run dropped sudo but two privileged test groups were
never tagged, and the Docker privileged job silently never ran the suite:
- Gate the ssh/server PrivilegeDropper command-construction tests behind
the privileged tag (they require root to target a different UID); split
them into executor_unix_privileged_test.go.
- Tag sharedsock raw-socket tests privileged (need CAP_NET_RAW).
- Fix the Docker job command: nested single quotes around the build tags
closed the sh -c wrapper early, dropping the go list package set and the
privileged tag, so go test ran on the empty repo root. Use double quotes.
Make the self-hosting harness usable from a dev Mac:
- Build it on darwin as well as linux; it only drives Docker.
- Resolve the active docker context endpoint into DOCKER_HOST when the
default /var/run/docker.sock is absent (Docker Desktop, Colima, OrbStack).
- Rename the misspelled containerGoModache constant to containerGoModCache.
