feat: add testing infrastructure (Vitest + Playwright)

[UfukCetinkaya57]

Summary

• Vitest + React Testing Library unit & component test altyapisi eklendi
• Playwright E2E test altyapisi eklendi (Chromium, Firefox, WebKit)
• Ornek testler: Home page (3 test), Button component (5 test), E2E navigation (4 test)
• CI workflow guncellendi: unit test + e2e job, artifact upload
• CLAUDE.md test kurallari ve dosya yapisiyla guncellendi

Eklenen Dosyalar

Dosya	Aciklama
vitest.config.ts	Vitest konfigurasyonu (jsdom, path alias, coverage)
vitest.setup.ts	jest-dom matcher'lari
playwright.config.ts	Playwright konfigurasyonu (3 browser, webServer)
__tests__/page.test.tsx	Home page unit testleri
__tests__/components/Button.test.tsx	Button component testleri
components/Button.tsx	Ornek Button component (test icin)
e2e/home.spec.ts	Home page E2E testleri

Script'ler

npm test              # Unit & component testleri calistir
npm run test:watch    # Izleme modunda calistir
npm run test:coverage # Coverage raporuyla calistir
npm run test:e2e      # E2E testleri calistir
npm run test:e2e:ui   # Playwright UI modunda calistir

Test plan

• Vitest 8/8 test gecti (lokal)
• CI uzerinde unit testlerin gectigini dogrula
• CI uzerinde E2E testlerin gectigini dogrula

🤖 Generated with Claude Code