Refactored everything into modules.

public/js/tts-handler.js

@@ -3,7 +3,7 @@
  * Enhanced version with improved voice selection, caching, and playback controls
  */
 
-class TTSHandler {
+export class TTSHandler {
   constructor() {
     this.enabled = false;
     this.speaking = false;
@@ -410,5 +410,5 @@ class TTSHandler {
   }
 }
 
-// Create a global instance
-const ttsHandler = new TTSHandler();
+// Create and export a singleton instance
+export const browserTtsHandler = new TTSHandler();