feat: refactor sidebar to nested draggable lists with long-press gesture arbitration

packages/app/src/utils/sidebar-reorder.ts

@@ -0,0 +1,21 @@
+export function mergeWithRemainder(input: {
+  currentOrder: string[]
+  reorderedVisibleKeys: string[]
+}): string[] {
+  const reorderedSet = new Set(input.reorderedVisibleKeys)
+  const remainder = input.currentOrder.filter((key) => !reorderedSet.has(key))
+  return [...input.reorderedVisibleKeys, ...remainder]
+}
+
+export function hasVisibleOrderChanged(input: {
+  currentOrder: string[]
+  reorderedVisibleKeys: string[]
+}): boolean {
+  const visibleSet = new Set(input.reorderedVisibleKeys)
+  const currentVisible = input.currentOrder.filter((key) => visibleSet.has(key))
+  if (currentVisible.length !== input.reorderedVisibleKeys.length) {
+    return true
+  }
+  return input.reorderedVisibleKeys.some((key, index) => currentVisible[index] !== key)
+}
+