test: isolate tests on void_test DB (stop resetDb wiping prod void)

resetDb() DROPs schema; dev DATABASE_URL pointed at the shared prod void DB on
.215. setup.js now forces a dedicated void_test DB (TEST_DATABASE_URL or derived)
and throws if it would target prod. Created void_test + pg_hba rule on CT 310.
Verified: full suite green, prod void space count unchanged (2→2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/helpers/setup.js

@@ -1 +1,24 @@
 import 'dotenv/config';
+
+// SAFETY GUARD — tests call resetDb() which runs `DROP SCHEMA public CASCADE`.
+// The dev DATABASE_URL points at the prod "void" database on the shared .215
+// cluster, so running tests against it WIPES PRODUCTION. Force a dedicated test
+// database here, and refuse to run if we'd still be pointed at "void".
+//
+// Resolution order:
+//   1. TEST_DATABASE_URL (explicit), else
+//   2. derive from DATABASE_URL by swapping the "/void" db name for "/void_test".
+const resolved =
+  process.env.TEST_DATABASE_URL ||
+  (process.env.DATABASE_URL || '').replace(/\/void(\?|$)/, '/void_test$1');
+
+if (!resolved || /\/void(\?|$)/.test(resolved)) {
+  throw new Error(
+    'Refusing to run tests: would target the prod "void" database. ' +
+    'Set TEST_DATABASE_URL to a dedicated test DB (e.g. .../void_test).'
+  );
+}
+
+// pool.js reads process.env.DATABASE_URL on first import; this setupFile runs
+// before the test module graph loads, so the pool binds to the test DB.
+process.env.DATABASE_URL = resolved;