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>

AGENTS.md

@@ -4,6 +4,10 @@ Deployment of the petrolyst server (atoma.petrolyst.com) and the Superset custom
 Runbook: README.md. Workspace rules: `../AGENTS.md`; shared context: `../.context/` (server and
 identity facts: `deployment.md`).
 
+**Architecture:** read `../.context/architecture.md` before planning or building. This repository
+runs persistence (fuel-db and its migrations) and Superset; name the bands a change touches and
+keep the rules there; a change against a rule or an open conflict goes to the owner first.
+
 ## Layout
 - `stacks/`, `traefik/`, `deploy/`, `host/`: how and where things run.
 - `petrolyst-insights/`: what Superset looks like and does (config, security manager, the guest