Web UI default port 8888; Lock now in the power menu

New installs put the Web UI on port 8888 instead of 8090 (existing installs
keep their port; change it under Addons -> Web UI, which now also closes the
old port in the firewall). The power menu gets a Lock now button, shown only
when password protection is on.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013wi3ZQveYdjfcrEsyazq32

lib/provision.sh

@@ -328,7 +328,7 @@ provision_configure_webui() {
         return 0
     fi
 
-    local port="8090"
+    local port="8888"
     webui_write_env_file "$port"
     webui_write_unit_file
     webui_write_helper_script