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/DashboardPage.ts

@@ -0,0 +1,56 @@
+/**
+ * Page object for the Dashboard (/dashboard).
+ *
+ * Maps to: frontend/src/pages/dashboard/DashboardPage.tsx
+ * Data: GET /api/reports/dashboard
+ */
+
+import { type Page, expect } from '@playwright/test';
+import { BasePage } from './BasePage';
+
+export class DashboardPage extends BasePage {
+  readonly path = '/dashboard';
+
+  // ─── Locators ────────────────────────────────────────────────
+
+  /** Main dashboard heading */
+  get heading() {
+    return this.page.getByRole('heading', { name: /dashboard/i }).first();
+  }
+
+  /** Account balance summary cards */
+  get balanceCards() {
+    return this.page.locator('[class*="Card"]').filter({ hasText: /balance|total/i });
+  }
+
+  /** Sidebar navigation */
+  get sidebar() {
+    return this.page.locator('nav').first();
+  }
+
+  /** Sidebar links */
+  sidebarLink(name: string) {
+    return this.sidebar.getByRole('link', { name });
+  }
+
+  // ─── Actions ─────────────────────────────────────────────────
+
+  /** Wait for dashboard data to load */
+  override async waitForReady(): Promise<void> {
+    await this.page.waitForLoadState('networkidle');
+    // Dashboard typically loads report data
+    await expect(this.page.locator('main')).toBeVisible();
+  }
+
+  /** Assert the dashboard has loaded with content */
+  async assertLoaded(): Promise<void> {
+    await this.assertOnPage();
+    await expect(this.page.locator('main')).not.toBeEmpty();
+  }
+
+  /** Navigate to a section via sidebar */
+  async navigateToSection(section: string): Promise<void> {
+    await this.sidebarLink(section).click();
+    await this.page.waitForLoadState('networkidle');
+  }
+}