feat: integrate Playwright for E2E testing and enhance testing framework

- Added Playwright for end-to-end testing in the `apps/web` module, including a new `login.spec.ts` for testing login functionality.
- Updated package.json to include Playwright dependencies and new test commands for E2E testing.
- Enhanced .gitignore to exclude Playwright test results and reports.
- Modified existing documentation to reflect the integration of Playwright and updated testing guidelines.
- Refactored test commands to streamline the testing process, including a dedicated command for E2E tests.

These changes improve the testing framework by providing robust E2E testing capabilities, enhancing the reliability and quality of the application.

.cursor/agents/tdd-guide.md

@@ -56,7 +56,7 @@ export const createFullPageSchema = (t: (key: string) => string) =>
 
 1. **Unit** — validators, transformers, utils, stores (`*.test.ts`)
 2. **Component** — Testing Library in packages that already have it
-3. **Journeys** — login and FULL_PAGE index / form / detail; mock `fullPageDataService`. Browser-verify layout/routing. See **e2e-runner**.
+3. **Journeys** — Playwright in `apps/web/e2e/` (copy `login.spec.ts`). Mock HTTP with `mockBackend`. See **e2e-runner**.
 
 ## Mocking