chore: clean up repo structure

- Add node_modules/, test-results/, e2e-report/, .omp/ to .gitignore
- Remove throwaway debug scripts (debug-pw*.js, debug-login-dom.js)
- Remove empty mock-server/ directory
- Untrack harness artifact (.omp/plans/)
- Add missing project files to git (e2e tests, Dockerfiles, tooling configs)

playwright.config.ts

@@ -0,0 +1,28 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './e2e',
+  // All tests mutate shared kernel state in the OpenWRT container; run serially.
+  fullyParallel: false,
+  workers: 1,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  reporter: [
+    ['html', { open: 'never', outputFolder: 'e2e-report' }],
+    ['list'],
+  ],
+  use: {
+    baseURL: 'http://localhost:8080',
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
+    video: 'on-first-retry',
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+  ],
+  timeout: 60_000,
+  expect: { timeout: 10_000 },
+});