test(dashboard): stabilize the e2e suite under parallel runs

Three issues found while running the full B1–B8 suite together:

- The B1 logout test was driving the shared admin storageState
  token, invalidating it for every subsequent test. Switched it to
  a fresh login so its session is disposable.
- Bumped navigationTimeout to 30s and capped local workers at 4 to
  cope with the Vite dev server's first-compile cost under
  parallel load. Local also gets one retry to absorb intermittent
  warmup flakiness.
- Cleared a few lint warnings (unused appId / _adminPage vars) and
  belt-and-braces gitignore for playwright artifacts written to
  the repo root when the CLI is invoked from there by accident.

Suite now: 55/55 passing in ~21s.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dashboard/tests/e2e/auth/auth.spec.ts

@@ -97,9 +97,16 @@ test.describe('B1 auth — authenticated', () => {
 		await page.goto('/admin/login');
 		await expect(page).toHaveURL(/\/admin\/apps$/);
 	});
+});
+
+test.describe('B1 auth — logout', () => {
+	// Logout must NOT use the shared storageState token, or it would
+	// invalidate the session every other test relies on. Each run
+	// here logs in fresh so its session is disposable.
+	test.use({ storageState: { cookies: [], origins: [] } });
 
 	test('logout clears the session and lands on /login', async ({ page }) => {
-		await page.goto('/admin/apps');
+		await loginAsAdmin(page);
 		await expect(page.getByRole('heading', { name: 'Apps', level: 1 })).toBeVisible();
 		await logout(page);
 		const token = await page.evaluate(() => localStorage.getItem('picloud.admin.token'));