fix: disable duplicate option for custom link

packages/nc-gui/components/smartsheet/header/Menu.vue

@@ -329,6 +329,7 @@ const isDuplicateAllowed = computed(() => {
     column?.value &&
     !column.value.system &&
     ((!isMetaReadOnly.value && !isDataReadOnly.value) || readonlyMetaAllowedTypes.includes(column.value?.uidt))
+    && !column.value.meta?.custom
   )
 })
 const isFilterSupported = computed(