Release 1.1.18: fix Sites page crash, refresh screenshots

The Sites & Replication page (added in the prior multi-master LDAP
release) 500'd on every load: views/sites.ejs included nonexistent
partials 'header'/'footer' instead of this app's actual 'top'/'bottom'.
Fixed to match every other view.

Also refreshed all README screenshots against the current UI and added
a new Sites & Replication screenshot.

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

nodejs/package.json

@@ -1,6 +1,6 @@
 {
   "name": "t42-sso-manager",
-  "version": "1.1.17",
+  "version": "1.1.18",
   "author": [
     {
       "name": "William Mantly",