Remove Trino: Superset reads fuel-db directly as fuel_ro (PD-14)

trino/ deleted; the role trino_ro becomes fuel_ro, its password read from a
secret file at connect time; dashboards' SQL and column list for PostgreSQL;
the Compose project is renamed petrolyst, with volumes pinned to their old
names. AGENTS.md points to the architecture context. Not deployed: the next
deploy needs README's one-time steps first.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

host/bootstrap.sh

@@ -40,7 +40,7 @@ if [ "$(cat /etc/docker/daemon.json 2>/dev/null)" != "$daemon_json" ]; then
 fi
 systemctl enable --now docker
 
-echo "== swap (4 GB) for Trino, Superset and two Postgres in 7.8 GB"
+echo "== swap (4 GB) for Superset and two Postgres in 7.8 GB"
 if ! swapon --show=NAME --noheadings | grep -qx /swapfile; then
   [ -e /swapfile ] || fallocate -l 4G /swapfile
   chmod 600 /swapfile