fix(e2e): add full E2E infrastructure (workflow, scripts, tests)

- Copy deploy/teardown scripts from add-e2e-infra branch
- Copy Playwright config and test files
- Add e2e script and @playwright/test devDependency
- Update E2E workflow to use pnpm-capable workflow branch with namespace param

PRI-634 follow-up

package.json

@@ -23,7 +23,8 @@
     "format": "prettier --write src/",
     "format:check": "prettier --check src/",
     "test": "vitest run",
-    "test:watch": "vitest"
+    "test:watch": "vitest",
+    "e2e": "playwright test"
   },
   "peerDependencies": {
     "react": "^18.0.0",
@@ -53,6 +54,7 @@
     "react-dom": "^18.3.1",
     "react-router-dom": "^5.3.0",
     "typescript": "~5.6.2",
-    "vitest": "^3.0.5"
+    "vitest": "^3.0.5",
+    "@playwright/test": "^1.58.2"
   }
 }