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-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "proxy-api",
-  "version": "1.1.17",
+  "version": "1.1.18",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "proxy-api",
-      "version": "1.1.17",
+      "version": "1.1.18",
       "license": "MIT",
       "dependencies": {
         "@fortawesome/fontawesome-free": "^7.3.0",