Enable auth-service/api-gateway on production, build their images in CI

apps/auth-service/src/db.ts

@@ -0,0 +1,10 @@
+import { Pool } from "pg";
+
+/** One pool per process, unlike ai-service's Postgres adapter (which opens a
+ * connection per call — see its own docstring on why that's a known, not-yet
+ * fixed gap there). Node's `pg.Pool` makes per-request pooling the default,
+ * cheap way to do this correctly from the start rather than inheriting that
+ * same gap in a second language. */
+export function createPool(dsn: string): Pool {
+  return new Pool({ connectionString: dsn, connectionTimeoutMillis: 5000 });
+}