feat: add apps/api (NestJS + Fastify) with authentication endpoints

- POST /auth/login, /auth/refresh, /auth/logout, /auth/select-tenant,
  /auth/change-password, GET /auth/tenants — wired to packages/auth
- JwtAuthGuard + DomainExceptionFilter (401/403 without leaking internals)
- LoginRateLimitGuard: Redis-backed 5/min per IP and per email (agente.md
  secao 149), safe across multiple API instances
- helmet + restrictive cors (deny-by-default) + global rate limit
- GET /health, /health/live, /health/ready checking Postgres and Redis
- changePassword() added to packages/auth for the mustChangePassword flow
- fixed REDIS_HOST/POSTGRES_HOST docker-compose-only hostnames not
  resolving from the host process; added REDIS_URL for host-side use
- verified end-to-end with curl: login, wrong password / unknown email
  (same generic error), authenticated route, missing token, refresh
  rotation, logout revocation, and the 429 rate limit kicking in after 5
  attempts

.env.example

@@ -3,3 +3,4 @@ DATABASE_URL=postgresql://user:password@localhost:5432/b2bcall?schema=public
 POSTGRES_APP_USER=
 POSTGRES_APP_PASSWORD=
 APP_DATABASE_URL=postgresql://user:password@localhost:5432/b2bcall?schema=public
+REDIS_URL=redis://:password@localhost:6379