Tela de Promotores adicionada ao Admin (source, sem build).

Entradas adicionadas:
- Aba "Promotores" na sidebar do admin
- Seção React: src/components/admin/sections/PromotersSection.tsx
- API admin:
  - GET /api/admin/promoters
  - POST /api/admin/promoters
  - PUT /api/admin/promoters/{id}
  - DELETE /api/admin/promoters/{id}

Arquivos alterados:
- src/components/admin/AdminSidebar.tsx
- src/components/admin/AdminView.tsx
- src/components/admin/sections/PromotersSection.tsx
- src/services/api.ts
- src/types.ts
- api/routes/admin.php
- api/lib/Repositories.php
- api/index.php

Observação:
- Mantido sem build.
- Tentei validar build, mas o ambiente atual não tinha o binário do Vite instalado sem rodar npm install.
