State that PgBouncer was measured, not assumed

The previous commit named PgBouncer as the pooler this client suits, from
background knowledge. It is now tested: PgBouncer 1.22 in transaction
mode (pool of 2, max_prepared_statements 0) passes every query that
hangs through pgCat 1.2.0, multiplexes 40 concurrent parameterised
queries over 2 server connections, and runs scripts/e2e-authz.sh to a
full PASS with 68 checks.

src/db/index.ts

@@ -19,9 +19,10 @@ import * as schema from "./schema";
 // so there is no subset of this app that works there.
 //
 // So `prepare: false` is necessary but nowhere near sufficient, and running
-// behind pgCat is an unverified claim rather than a tested path. PgBouncer is
-// the pooler this configuration is actually known to suit. Migrations go
-// straight at Postgres regardless - drizzle.config.ts has no way to pass
+// behind pgCat does not work. PgBouncer 1.22 in transaction mode does: the
+// same queries pass, 40 concurrent ones multiplex over a pool of 2 server
+// connections, and scripts/e2e-authz.sh passes all 68 checks through it.
+// Migrations go straight at Postgres regardless - drizzle.config.ts has no way to pass
 // `prepare: false`, and drizzle-kit hung at commit for the same reason.
 const connectionString = process.env.DATABASE_URL;
 if (!connectionString) {