test: usar setDb(memdb) en admin.test.ts

Co-authored-by: aider (openrouter/openai/gpt-5) <aider@aider.chat>

tests/unit/services/admin.test.ts

@@ -11,8 +11,7 @@ describe('AdminService - comandos básicos', () => {
   beforeEach(() => {
     process.env = { ...envBackup, NODE_ENV: 'test', ADMIN_USERS: '34600123456' };
     memdb = makeMemDb();
-    (AdminService as any).dbInstance = memdb;
+    setDb(memdb);
-    (AllowedGroups as any).dbInstance = memdb;
     AllowedGroups.resetForTests();
   });