feat: add Playwright E2E and API regression test suite

Production-ready test infrastructure with Page Object Model pattern,
reusable fixtures for auth/DB/test-data, and example tests covering
login flow, dashboard, accounts CRUD API, and visual regression.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/page-objects/index.ts

@@ -0,0 +1,10 @@
+/**
+ * Re-export all page objects for convenient imports.
+ *
+ * Usage: import { LoginPage, DashboardPage } from '../page-objects';
+ */
+
+export { BasePage } from './BasePage';
+export { LoginPage } from './LoginPage';
+export { DashboardPage } from './DashboardPage';
+export { AccountsPage } from './AccountsPage';