fix: Add missing whats-new-dismissed event emission in WhatsNewPopup

During merge with main, the event emission was lost from the hide() function.
- Add defineEmits for 'whats-new-dismissed' event
- Emit event in hide() function to maintain test compatibility
- Fixes 3 failing unit tests in WhatsNewPopup.test.ts

src/components/helpcenter/WhatsNewPopup.vue

@@ -75,6 +75,11 @@ import { formatVersionAnchor } from '@/utils/formatUtil'
 const { locale, t } = useI18n()
 const releaseStore = useReleaseStore()
 
+// Define emits
+const emit = defineEmits<{
+  'whats-new-dismissed': []
+}>()
+
 // Local state for dismissed status
 const isDismissed = ref(false)
 
@@ -126,6 +131,7 @@ const show = () => {
 
 const hide = () => {
   isDismissed.value = true
+  emit('whats-new-dismissed')
 }
 
 const closePopup = async () => {