feat: add React frontend

[Siya360]

Summary

• integrate Vite + React frontend under frontend/
• wire up frontend service in docker compose with environment variables
• document frontend development and full-stack compose usage
• remove leftover merge text from README
• connect Go flights service to Amadeus API with /flights/search
• expose Amadeus credentials via compose and service docs

Testing

• go vet ./... (flights)
• go build -o /tmp/flights ./cmd
• bun install
• bun test
• bun run lint (fails: react-refresh/only-export-components, @typescript-eslint/no-empty-object-type, @typescript-eslint/no-explicit-any, @typescript-eslint/no-require-imports)
• python -m py_compile agents/orchestrator/main.py

---

https://chatgpt.com/codex/tasks/task_e_689f411cea408333b4bb76652a0206e4