Add E2E test infrastructure for kube-vip plugin

Scaffolded via e2e-scaffold.sh (proactive improvement).
- playwright.config.ts, e2e/auth.setup.ts, e2e/kube-vip.spec.ts
- scripts/deploy-e2e-headlamp.sh, scripts/teardown-e2e-headlamp.sh
- .github/workflows/e2e.yaml uses reusable workflow
- @playwright/test ^1.58.2 devDep

- PRI-641

Co-Authored-By: Paperclip <noreply@paperclip.ing>

e2e/kube-vip.spec.ts

@@ -0,0 +1,42 @@
+import { test, expect } from '@playwright/test';
+
+test.describe('kube-vip plugin smoke tests', () => {
+  test('sidebar contains kube-vip entry', async ({ page }) => {
+    await page.goto('/');
+    const sidebar = page.getByRole('navigation', { name: 'Navigation' });
+    await expect(sidebar).toBeVisible({ timeout: 15_000 });
+    await expect(sidebar.getByRole('button', { name: /kube.vip/i })).toBeVisible();
+  });
+
+  test('kube-vip sidebar entry navigates to kube-vip view', async ({ page }) => {
+    await page.goto('/');
+    const sidebar = page.getByRole('navigation', { name: 'Navigation' });
+    await expect(sidebar).toBeVisible({ timeout: 15_000 });
+
+    const entry = sidebar.getByRole('button', { name: /kube.vip/i });
+    await expect(entry).toBeVisible();
+    await entry.click();
+
+    await expect(page).toHaveURL(/kube-vip/);
+    await expect(page.getByRole('heading', { name: /kube.vip/i })).toBeVisible();
+  });
+
+  test('kube-vip page renders content', async ({ page }) => {
+    await page.goto('/c/main/kube-vip');
+
+    await expect(page.getByRole('heading', { name: /kube.vip/i })).toBeVisible({
+      timeout: 15_000,
+    });
+
+    const hasTable = await page.locator('table').first().isVisible().catch(() => false);
+    const hasContent = await page.locator('[class*="Mui"]').first().isVisible().catch(() => false);
+    expect(hasTable || hasContent).toBe(true);
+  });
+
+  test('plugin settings page shows kube-vip plugin entry', async ({ page }) => {
+    await page.goto('/settings/plugins');
+
+    const pluginEntry = page.locator('text=/kube.vip/i').first();
+    await expect(pluginEntry).toBeVisible({ timeout: 30_000 });
+  });
+});