install the psql client, matching the server it talks to

there was no psql on this machine. the server runs in a container, so nothing
ever put a client on the host, and `docker exec officer-postgres psql` is the
owner's tool — a member has their own Postgres role and no access to the owner's
Docker socket.

the version is derived from PG_IMAGE rather than typed again, because the
pairing is load-bearing: pg_dump refuses a server newer than itself, and Ubuntu
24.04 ships client 16 against this 18 server. so the archive package is not
merely old, it is unusable for dumps. that is also why this sits beside the
server definition instead of in machine-setup's package list — one constant, one
place to bump.

PGDG added the same way docker.sh adds Docker's: key in its own file, one
sources.list.d entry, no add-apt-repository. non-fatal, and the exit status is
not the gate — apt can succeed while holding an older client back, so the check
is that psql is present AND is the major we asked for.

installed by hand on this host already: psql/pg_dump 18.6, verified as green
connecting with their own role.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/setup/officer-setup.sh

@@ -446,6 +446,11 @@ if ! skip; then
     echo "     network:       ${OFFICER_NETWORK} (already there)"
   fi
 
+  # The client goes on the HOST, before any of the container work, because it is the half
+  # that is not in the container. A member has their own Postgres role and no access to the
+  # owner's Docker socket, so `docker exec … psql` is the owner's tool, not theirs.
+  install_pg_client || ERRORS+=("psql: client not installed — members have no Postgres CLI")
+
   echo "     compose file:  $(pg_compose_exists && echo "$(pg_compose_file)" || echo 'not written yet')"
   echo "     container:     $(pg_container_running && echo "${PG_CONTAINER} running" || echo 'not running')"
   echo "     port ${PG_PORT}:    $(pg_port_in_use && echo 'something is listening' || echo 'free')"