Add E2E tests to stop hook and README

- Stop hook now triggers on frontend/e2e/ changes
- Stop hook runs Playwright E2E tests alongside unit tests
- README documents test:e2e command and Playwright in code quality section

README.md

@@ -65,8 +65,11 @@ fete/
 # Backend
 cd backend && ./mvnw test
 
-# Frontend
+# Frontend unit tests
 cd frontend && npm run test:unit
+
+# Frontend E2E tests (requires Chromium: npx playwright install chromium)
+cd frontend && npm run test:e2e
 ```
 
 ### Running the backend locally
@@ -138,11 +141,12 @@ ArchUnit enforces hexagonal boundaries: domain must not depend on adapters, appl
 | TypeScript (strict) | `vue-tsc --noEmit` | Type errors     |
 | oxlint + ESLint     | `oxlint`, `eslint` | Lint violations |
 
-**When the agent finishes** (Stop hook — only if `frontend/src/` has uncommitted changes):
+**When the agent finishes** (Stop hook — only if `frontend/src/` or `frontend/e2e/` has uncommitted changes):
 
 | What                | Command                      | Fails on                              |
 |---------------------|------------------------------|---------------------------------------|
 | Vitest              | `npm run test:unit -- --run` | Test failures (fail-fast, stops at 1) |
+| Playwright          | `npm run test:e2e`           | E2E test failures                     |
 
 **Not hooked** (run manually or via editor):