types: improve relation types (#9016)

src/grid/Grid.tsx

@@ -1,12 +1,10 @@
-import { PropType, defineComponent, ExtractPropTypes } from 'vue';
+import { PropType, defineComponent, ExtractPropTypes, InjectionKey } from 'vue';
 import { createNamespace, addUnit, truthProp } from '../utils';
 import { BORDER_TOP } from '../utils/constant';
 import { useChildren } from '@vant/use';
 
 const [name, bem] = createNamespace('grid');
 
-export const GRID_KEY = Symbol(name);
-
 export type GridDirection = 'horizontal' | 'vertical';
 
 const props = {
@@ -28,6 +26,8 @@ export type GridProvide = {
   props: ExtractPropTypes<typeof props>;
 };
 
+export const GRID_KEY: InjectionKey<GridProvide> = Symbol(name);
+
 export default defineComponent({
   name,