test(desktop): Playwright electron e2e harness

Launches the built app (out/main/index.js) via Playwright's _electron
API — no browser project, no chromium download. Adds a launch fixture
(electronApp/window/app), an AppPage page object with a screenshot
helper for autonomous visual review, and a boot smoke suite (shell
renders, @commitea/core label-parse runs in the renderer, preload API
exposed). Scripts: e2e (build+run), e2e:only, e2e:report. Artifacts
gitignored.

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

apps/desktop/e2e/smoke.spec.ts

@@ -0,0 +1,19 @@
+import { expect, test } from './fixtures.js'
+
+test('boots and renders the CommiTea shell', async ({ app }) => {
+  await app.expectLoaded()
+  await app.screenshot('boot')
+})
+
+test('renders the label-parse check from @commitea/core', async ({ window }) => {
+  // Proves the core package is bundled + running in the renderer, not just
+  // that the window opened. Updates as the scaffold gives way to real screens.
+  await expect(window.getByText(/label parse check/i)).toBeVisible()
+  await expect(window.getByText(/est\/3d · p\/2 · hard true/)).toBeVisible()
+})
+
+test('exposes the commitea preload API', async ({ app }) => {
+  const api = await app.preloadApi()
+  expect(api).toBeDefined()
+  expect(api).toHaveProperty('platform')
+})