All 13 nginx embed proxy ports (8881-8895) are now driven by environment
variables instead of being hardcoded. This prevents port conflicts when
running multiple Changemaker instances on the same host.
Chain: .env → docker-compose port mappings → nginx container env →
entrypoint.sh envsubst → services.conf.template listen directives →
API /services/config endpoint → frontend buildServiceUrl().
Existing deployments are unaffected (all vars default to current values).
Bunker Admin
