Scaffold frontend (Vite + React + TS) with lint, Prettier and Vitest

[ivankoc]

Acceptance criteria

• frontend/ created with Vite React TS template
• ESLint + Prettier configured, npm run lint and npm run format scripts
• Vitest + Testing Library with one example test
• Vite base set to /project2/ for the VM
• Commands documented in README.md and CLAUDE.md "Repo layout"

[ivankoc]

Done on branch chore/4-init-setup in #7. The issue closes automatically when #7 is merged.