feat: add comprehensive testing infrastructure

- Add Vitest for unit testing across all packages
- Add Playwright for E2E testing
- Add sample tests for API, Web, and Shared packages
- Configure Gitea Actions CI/CD workflows (ci, e2e, security, docker)
- Add testing documentation (TESTING.md)
- Add Gitea Actions setup guide
- Update .gitignore for test artifacts
- Add test environment configuration

packages/web/vitest.setup.ts

@@ -0,0 +1,11 @@
+import { expect, afterEach } from 'vitest';
+import { cleanup } from '@testing-library/react';
+import '@testing-library/jest-dom/vitest';
+
+// Cleanup after each test case (e.g., clearing jsdom)
+afterEach(() => {
+  cleanup();
+});
+
+// Extend Vitest matchers with jest-dom
+expect.extend({});