test: add messaging screen e2e guard (tabs + history render)

Guards the messaging screen (Send/Bulk/History tabs and the message-history
list against mocked data) before decomposing the 1051-line message-history
component.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/e2e/messaging.spec.ts

@@ -0,0 +1,39 @@
+import { expect, test } from '@playwright/test'
+import { authenticate } from './session'
+import { mockApi } from './mock-api'
+
+test.describe('messaging (mocked API, no real backend)', () => {
+  test('renders the messaging screen and its tabs', async ({
+    page,
+    context,
+  }) => {
+    await authenticate(context)
+    await mockApi(page)
+    await page.goto('/dashboard/messaging')
+
+    await expect(
+      page.getByRole('heading', { name: 'Messaging', level: 2 })
+    ).toBeVisible()
+    // Tab list is present.
+    await expect(
+      page.getByRole('tab', { name: 'Send', exact: true })
+    ).toBeVisible()
+    await expect(page.getByRole('tab', { name: 'History' })).toBeVisible()
+  })
+
+  test('history tab loads mocked messages without crashing', async ({
+    page,
+    context,
+  }) => {
+    await authenticate(context)
+    await mockApi(page)
+    await page.goto('/dashboard/messaging')
+
+    await page.getByRole('tab', { name: 'History' }).click()
+
+    // Mocked device message body from the fixtures.
+    await expect(page.getByText('Hello from textbee')).toBeVisible()
+    // Never fell through to an error boundary.
+    await expect(page.getByText('This page couldn')).toHaveCount(0)
+  })
+})