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>

secrets.js.example

@@ -67,12 +67,14 @@ module.exports = {
         adminUsers: ['proxyadmin'],
         groupRoleMap: {},
         // Optional: the local anti-lockout admin's initial password, used
-        // ONLY the first time that account is created. Leave unset and it
-        // defaults to the username itself ("proxyadmin2") — fine for a quick
-        // local test, but change it (or set this) before exposing the proxy
-        // publicly. Once the account exists, this key is never read again;
-        // change the password via the app itself (or delete the Redis user
-        // to force it to be re-bootstrapped with a new value here).
+        // ONLY the first time that account is created. Leave unset and a
+        // random password is generated and printed to the container log on
+        // first boot — fine for a quick local test if you copy it from the
+        // log right away, but set this (or change the password afterward)
+        // before exposing the proxy publicly. Once the account exists, this
+        // key is never read again; change the password via the app itself
+        // (or delete the Redis user to force it to be re-bootstrapped with a
+        // new value here).
         // localAdminPass: 'change-me',
     },