feat(VocabPracticeDialog, VocabCourseView): implement event dispatch for hard vocabulary changes

- Added event dispatching for 'yourpart:hardvocab:changed' in both VocabPracticeDialog and VocabCourseView components to notify changes in hard vocabulary items.
- Implemented event handling in VocabCourseView to refresh the hard vocabulary list when the event is triggered, ensuring UI consistency across components.
- Included error handling for environments that do not support CustomEvent, enhancing robustness.

frontend/src/dialogues/socialnetwork/VocabPracticeDialog.vue

@@ -339,6 +339,16 @@ export default {
       } catch (_) {
         // ignore quota/private-mode issues
       }
+      try {
+        window.dispatchEvent(new CustomEvent('yourpart:hardvocab:changed', {
+          detail: {
+            courseId: this.openParams?.courseId || null,
+            storageKey: key
+          }
+        }));
+      } catch (_) {
+        // ignore environments without CustomEvent
+      }
     },
     getHardKey(item) {
       const learning = this.normalize(item?.learning || '');