Pagination for secrets

The list action of the runtime_secrets MCP tool now supports pagination with limit (1 to 100) and after, as its schema documents. Pagination is also supported by GET /v1/egress-secrets (pass the response's next value as after to get the next page), secrets.list in every SDK, and runtime secrets ls --limit --after. The runtime_secrets schema now states which action accepts each field, and a field sent to the wrong action returns an error that names the correct one.