Fix language code detection: load supported languages on module init

Ensure SUPPORTED_LANGUAGES in language-constants.js is populated with all 55 codes
before event handlers run, so isLanguageCode() works correctly. Prevents duplicate
language codes like [hr:|hr:|...] by properly detecting language codes vs parameters.

web/widget-event-handlers.js

@@ -215,8 +215,8 @@ export function attachAllEventHandlers(
                 if (isLanguageCode(beforeColon)) {
                     // It's already a language tag - only update if language is different
                     if (beforeColon === lang) {
-                        // Same language already exists, don't add duplicate
-                        return null;
+                        // Same language already exists, return unchanged
+                        return tagContent;
                     } else {
                         // Replace the language part with new language
                         const charPart = firstPart.substring(colonIndex + 1);

web/widget-ui-builder.js

@@ -5,6 +5,10 @@
  */
 
 import { TagUtilities } from "./tag-utilities.js";
+import { loadSupportedLanguages } from "./language-constants.js";
+
+// Load supported languages into memory on module load
+loadSupportedLanguages();
 
 export function buildHistorySection(state, storageKey) {
     const historySection = document.createElement("div");