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>

petrolyst-insights/superset_config.py

@@ -45,6 +45,21 @@ SQLALCHEMY_DATABASE_URI = URL.create(
     database="superset",
 ).render_as_string(hide_password=False)
 
+# --- The data: fuel-db ----------------------------------------------------------
+# Superset reads fuel-db directly as the read-only role fuel_ro (no Trino since 29 Oct 2026);
+# superset-init registers that connection, "Fuel", without a password. Passwords of data
+# connections come from secret files at connect time, so none is kept in Superset's own
+# database. A connection added in the UI gets no password this way.
+_DATABASE_PASSWORD_SECRETS = {"fuel_ro": "fuel_db_ro_password"}
+
+
+def _database_password(url: URL) -> str | None:
+    secret = _DATABASE_PASSWORD_SECRETS.get(url.username or "")
+    return _read_secret(secret) if secret else None
+
+
+SQLALCHEMY_CUSTOM_PASSWORD_STORE = _database_password
+
 # --- Sign-in through Keycloak (client "petrolyst") ----------------------------
 # Users and roles are managed in Keycloak; there is no local admin account.
 # Break-glass access: `superset fab ...` inside the container on the server.