fix(bootstrap): site-relay-register.js used the wrong login field for jump-host

jump-host's local admin login (via @simpleworkjs/oidc-client's shared
router) expects `username`, not `uid` -- sso-manager-node's own
/api/auth/login (used by site-join.js) is the one that expects `uid`.
Caught live: the script's login call to jump-host silently 401'd with
`uid`. Confirmed against a real jump-host container that `username`
succeeds.

bootstrap/site-relay-register.js

@@ -76,7 +76,11 @@ async function main() {
   const loginRes = await fetch(`${JUMP_INTERNAL}/api/auth/login`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ uid: jumpAdminUser, password: jumpAdminPass }),
+    // jump-host's login route (@simpleworkjs/oidc-client's shared router)
+    // expects `username`, not `uid` -- unlike sso-manager-node's own
+    // /api/auth/login (see site-join.js). Confirmed against a real running
+    // jump-host container; `uid` here just silently 401s.
+    body: JSON.stringify({ username: jumpAdminUser, password: jumpAdminPass }),
   });
   if (!loginRes.ok) {
     throw new Error(`jump-host admin login failed (${loginRes.status}): ${await loginRes.text().catch(() => '')}`);