Add AUTH_STACK so the Auth tab follows the stack in force

Authentik is the likely destination and the page had Authelia and lldap wired in at every
level, so the seam goes in now: the panels and every endpoint action route off one conf value,
and a stack that cannot be driven yet says so rather than drawing controls with nothing behind.

Plugin/unraid/include/confform.php

@@ -128,7 +128,7 @@ const VV_UI_SECTION_SURFACES = [
     // is what its Certs panel reports. The credentials in particular belong on the page that fails
     // without them: a blank NPM_USER surfaces there as a refused login, and the fix is two panels
     // away rather than in a hundred-and-twenty-field catch-all.
-    ['match' => 'NginxProxyManager|lldap|Authelia|Certificate Monitor', 'tab' => 'Auth',
+    ['match' => 'Auth Stack|NginxProxyManager|lldap|Authelia|Certificate Monitor', 'tab' => 'Auth',
      'route' => 'Auth tab → Auth settings'],
 
     // Everything that is not structurally excluded. The catch-all exists so no ordinary setting