refactor(vocab): unify text normalization across VocabService and VocabPracticeDialog

- Enhanced text normalization methods in VocabService and VocabPracticeDialog to include normalization and improved regex for punctuation and symbols, ensuring consistent text handling.
- This update streamlines the normalization process, contributing to better user input processing and overall application reliability.

backend/services/vocabService.js

@@ -342,12 +342,14 @@ export default class VocabService {
   }
 
   _normalizeTextAnswer(text) {
-    return String(text || '')
+    const normalized = String(text || '')
       .trim()
       .toLowerCase()
-      .replace(/[\p{P}]+/gu, ' ')
+      .normalize('NFKC')
+      .replace(/[\p{P}\p{S}]+/gu, ' ')
       .replace(/\s+/g, ' ')
       .trim();
+    return normalized.replace(/\s+/g, '');
   }
 
   _parseExercisePayload(value) {