8c184a7f9a
A no-inbound spoke's join script (theta-suite's bootstrap/site-join.js) needs its own gateway's mesh IP to hand to sso-manager-node's /api/site/join, but the only existing read (GET /api/mesh/gateways) requires a full jump-admin session -- unusable from an unattended bootstrap script. Add a narrower read gated only by a valid jmp_ API token (any self-service token, same as theta-proxy's prx_ tokens for proxy_client.js), exposing just this gateway's own mesh IP.