feat: redesign task detail paper flow

frontend/src/composables/useOverlayStack.ts

@@ -77,6 +77,11 @@ export function popOverlay(id: symbol) {
   })
 }
 
+export function overlayZIndex(id: symbol | null) {
+  const index = id ? stack.findIndex((entry) => entry.id === id) : -1
+  return 80 + Math.max(0, index)
+}
+
 export function isTopOverlay(id: symbol | null) {
   return Boolean(id && stack.at(-1)?.id === id)
 }