Release 1.1.18: fix bootstrap admin lockout, refresh screenshots

models/user_redis.js hardcoded the bootstrap anti-lockout admin
username to 'proxyadmin2', while migrations/permission_bootstrap.js
grants the global-admin permission to conf.auth.adminUsers[0]. An
operator who customized adminUsers away from the default ended up
with a bootstrapped account that had no admin permissions -- a
silent lockout. user_redis.js now derives the bootstrap username the
same way permission_bootstrap.js does.

Also corrected a secrets.js.example comment that claimed the
bootstrap password defaults to the username itself (it actually
generates and logs a random password), and refreshed all README
screenshots against the current UI, including a new load-balancing
screenshot.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

nodejs/package.json

@@ -1,6 +1,6 @@
 {
   "name": "proxy-api",
-  "version": "1.1.17",
+  "version": "1.1.18",
   "author": [
     {
       "name": "William Mantly",