fix(plugin-grid): rename the grouping hook's local field type off a spec-owned name (slice 6)

check:spec-symbols refuses a local `ObjectFieldLike` because
@objectstack/spec/system exports that name. The local type is
GroupingFieldDef now; nothing else changes.

Co-authored-by: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdrd2yH4eqnz2QobtN3haE

Author: claude

ui/packages/plugin-grid/src/objectGridGrouping.ts

@@ -25,7 +25,7 @@ type QueryInputs = ReturnType<typeof useObjectGridQueryInputs>;
 type GroupingDecisions = ReturnType<typeof useObjectGridGroupingDecisions>;
 type RowLoad = ReturnType<typeof useObjectGridRowLoad>;
 /** What the grouping reads off an object field: its cell face and its options. */
-type ObjectFieldLike = GridCellFieldLike & {
+type GroupingFieldDef = GridCellFieldLike & {
   type?: string;
   options?: Parameters<ReturnType<typeof useSafeFieldLabel>['translateOptions']>[2];
 };
@@ -93,7 +93,7 @@ export function useObjectGridGrouping({
   schema: ObjectGridSchema;
   dataSource: DataSource | undefined;
   objectName: string | undefined;
-  objectFields: Readonly<Record<string, ObjectFieldLike | undefined>> | undefined;
+  objectFields: Readonly<Record<string, GroupingFieldDef | undefined>> | undefined;
   objectTypesPending: boolean;
   data: unknown[];
   setData: React.Dispatch<React.SetStateAction<unknown[]>>;