big restructure

web/js/components/app-async-flash.js

@@ -1,3 +1,5 @@
+import { warnOnce } from '../core/app-dom.js';
+
 /**
  * Async Flash Messages & Loading State
  * Renders flash messages into #async-messages for JS-triggered notifications
@@ -46,7 +48,7 @@ const defaultTimeouts = {
 export function showAsyncFlash(type, message, timeout) {
   const container = document.getElementById('async-messages');
   if (!container) {
-    console.warn('async-messages container not found');
+    warnOnce('UI_EL_MISSING', 'Missing #async-messages container', { module: 'async-flash' });
     return null;
   }