Let one gate decide every AI surface, so switching AI off actually removes all of it

The Tools card adopted the AI scripts on the host check alone, and api/ai.php only
tested AI_ENABLED in front of ask, so a disabled subsystem still had rows to run and
an endpoint that answered.

Plugin/unraid/Varaverk.page

@@ -83,8 +83,7 @@ $validTabs = ['monitor', 'scheduler', 'docker', 'watchdog', 'partnership', 'fall
 // include/ai.php only ever reads the *local* {HOST}_OLLAMA_URL — there is no Tailscale resolver
 // in the PHP layer the way there is in the shell. On any other host the tab could only render
 // and then fail its own health check.
-$_vv_ai = vv_is_ai_host()
-       && strtolower(trim(vv_conf_vars()['AI_ENABLED'] ?? 'false')) === 'true';
+$_vv_ai = vv_ai_ui_on();
 if ($_vv_ai) $validTabs[] = 'ai';
 
 if (!in_array($tab, $validTabs)) $tab = 'monitor';