feat(migrate): containr migrate railway — GraphQL import of services/vars/domains

--token (or RAILWAY_TOKEN) reads the Railway project via backboard
GraphQL: services resolve to git-repo or image services with command +
replicas, variables and service/custom domains follow. --dry-run prints
the plan; --into targets an existing project. Both account (Bearer) and
project tokens (Project-Access-Token header) work.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

docs/guides/CLI.md

@@ -72,6 +72,7 @@ import compose <project-id> <compose.yml|->
                                attached under their service name; --var K=V overrides
                                template variables
 nodes list|get|delete|tokens     node agents + onboarding tokens (admin)
+migrate railway                  pull a Railway project (services, vars, domains) via GraphQL and recreate it — --dry-run prints the plan
 scaling status|policies|services|scale
 ha status|alerts|health|policies|enable|disable|failover
 security scan|vulnerabilities|metrics