add electron e2e harness and regression coverage (#697)

playwright.config.ts

@@ -0,0 +1,22 @@
+import { defineConfig } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: false,
+  workers: 1,
+  forbidOnly: Boolean(process.env.CI),
+  retries: process.env.CI ? 2 : 0,
+  timeout: 90_000,
+  expect: {
+    timeout: 15_000,
+  },
+  reporter: [
+    ['list'],
+    ['html', { open: 'never' }],
+  ],
+  use: {
+    trace: 'retain-on-failure',
+    screenshot: 'only-on-failure',
+    video: 'retain-on-failure',
+  },
+});