9d266d2e4c
Completes the multi-site join layer on top of the v2.2.0 endpoints: - UI (Master Site modal): a fresh install (canJoin) gets a 'Join an Existing Site' form (master URL + stj_ key); a master gets a 'Site Join Keys' manager (mint/revoke/list, key shown once); WAN Sync Health now reflects a live probe. - POST /api/site/ping (Bearer stj_ key, no admin session): lightweight master reachability probe for WAN health (cheap vs /export). - Spoke read-only: directory-write routes (resources/edges/groups/secrets/ grants/driver-action/discovered) reject with 403 pointing at the master. - Fresh-install guard: /api/site/join refuses unless no users beyond the bootstrap admin and no enrolled agents (siteIsFresh), and site-status exposes canJoin so the UI only offers join on a genuinely fresh install. The bootstrap's seeded default resources are NOT the signal (they always exist). - The spoke stores the join key (masterJoinKey) in /config/site.json so WAN health (and a future write-proxy) can reach the master. - Tests: siteIsFresh cases in tests/site_join.test.js.