feat: initialize main app module with data loading and UI setup

js/app.js

@@ -2,9 +2,16 @@
  * Main Application Module
  * Entry point for the application, initializes all components
  */
-document.addEventListener('DOMContentLoaded', () => {
+document.addEventListener('DOMContentLoaded', async () => {
     // Initialize all modules
-    DataManager.init();
+    try {
+        await DataManager.init(); // Wait for data to be loaded and processed
+    } catch (error) {
+        console.error('Failed to initialize DataManager:', error);
+        // Optionally, display an error message to the user in the UI
+        // For example, by setting some text in a dedicated error div.
+        // For now, we'll log and let the app proceed with potentially empty/default data.
+    }
     UI.init();
     Charts.init();