Alteracoes:
- Configura .env do backend-old com DATABASE_URL e porta 8214
- Atualiza server.go com correcoes de servidor
- Adiciona package-lock.json e atualiza package.json do backend Medusa
- Adiciona docker-compose.yml para servicos locais
- Corrige authUtils.ts e CadastroProdutoWizard.tsx no frontend
- remove backend-old (Medusa), saveinmed-frontend (Next.js/Appwrite) and marketplace dirs
- split Go usecases by domain and move notifications/payments to infrastructure
- reorganize frontend pages into auth, dashboard and marketplace modules
- add Makefile, docker-compose.yml and architecture docs