Use clone for itemviewer trim

frontend/components/item/Tree.vue

@@ -80,7 +80,7 @@ addEventListener('resize', (_) => {
 })
 addEventListener("scroll", (_) => {
     refreshArrows()
-});
+})
 
 function handleSubtreeMount(end : Element) {
     drawArrow(start.value!!, end)

frontend/components/item/Viewer.vue

@@ -9,9 +9,14 @@ for(let item of items.value) {
     itemMap.set(item.id, item)
 }
 
-watch(() => props.builds, () => trimBuilds(props.builds))
-trimBuilds(props.builds)
-trimLateGameItems(props.builds)
+const builds = ref(JSON.parse(JSON.stringify(props.builds)))
+watch(() => props.builds, () => {
+    builds.value = JSON.parse(JSON.stringify(props.builds))
+    trimBuilds(builds.value)
+    trimLateGameItems(builds.value)
+})
+trimBuilds(builds.value)
+trimLateGameItems(builds.value)
 
 function trimBuilds(builds : Builds) {
     builds.tree.children.splice(1, builds.tree.children.length - 1)