message: types: improve use relation typing
diff: import { ref, Ref, provide, inject, computed, onUnmounted } from 'vue';
  -export type Parent = null | {
  - children: Ref<unknown[]>;
  +export type Parent<T = unknown> = null | {
  + children: Ref<Ref<T>[]>;
  };
  export function useChildren(key: string) {
  @@ -10,8 +10,8 @@ export function useChildren(key: string) {
  return children;
  }
  -export function useParent(key: string, child: unknown) {
  - const parent = inject<Parent>(key, null);
  +export function useParent<T = unknown>(key: string, child: Ref<T>) {
  + const parent = inject<Parent<T>>(key, null);
  if (parent) {
  const children = parent.children.value;
  