Add web shell, build and deploy scripts, Playwright smoke

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

web/playwright.config.js

@@ -0,0 +1,13 @@
+import { defineConfig } from '@playwright/test'
+
+// BASE_URL runs the tests against a deployed site.
+const url = process.env.BASE_URL
+
+export default defineConfig({
+  testDir: 'tests',
+  timeout: 90000,
+  use: { baseURL: url || 'http://localhost:4173', viewport: { width: 1280, height: 820 } },
+  webServer: url
+    ? undefined
+    : { command: 'python3 -m http.server 4173 --directory dist', url: 'http://localhost:4173', reuseExistingServer: true }
+})