fix(modal): prevent duplicate ModalManager declaration

window.ModalManager was set unconditionally, causing "Identifier
'ModalManager' has already been declared" when script tag in HTML
also loaded ModalManager before renderer.js required it.

Now checks !window.ModalManager before setting.

Amit Haridas

src/utils/ModalManager.js

@@ -237,8 +237,8 @@ class ModalManager {
     }
 }
 
-// Export for use in renderer
-if (typeof window !== 'undefined') {
+// Export for use in renderer - avoid duplicate declaration
+if (typeof window !== 'undefined' && !window.ModalManager) {
     window.ModalManager = ModalManager;
 }