refactor: extract resolveColumnLabel helper for I18nLabel type safety in ObjectGrid

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/plugin-grid/src/ObjectGrid.tsx

@@ -23,6 +23,7 @@
 
 import React, { useEffect, useState, useCallback, useMemo } from 'react';
 import type { ObjectGridSchema, DataSource, ListColumn, ViewData } from '@object-ui/types';
+import type { I18nLabel } from '@objectstack/spec/ui';
 import { SchemaRenderer, useDataScope, useNavigationOverlay, useAction, useObjectTranslation, useSafeFieldLabel } from '@object-ui/react';
 import { getCellRenderer, formatCurrency, formatCompactCurrency, formatDate, formatPercent, humanizeLabel } from '@object-ui/fields';
 import {
@@ -90,6 +91,13 @@ function useGridTranslation() {
   }
 }
 
+/** Resolve an I18nLabel (string | {key, defaultValue}) to a plain string. */
+function resolveColumnLabel(label: string | I18nLabel | undefined): string | undefined {
+  if (label == null) return undefined;
+  if (typeof label === 'string') return label;
+  return label.defaultValue || label.key;
+}
+
 export interface ObjectGridProps {
   schema: ObjectGridSchema;
   dataSource?: DataSource;
@@ -619,8 +627,7 @@ export const ObjectGrid: React.FC<ObjectGridProps> = ({
           return (cols as ListColumn[])
             .filter((col) => col?.field && typeof col.field === 'string' && !col.hidden)
             .map((col, colIndex) => {
-              const rawLabel = col.label;
-              const rawHeader = (typeof rawLabel === 'string' ? rawLabel : typeof rawLabel === 'object' && rawLabel ? (rawLabel as any).defaultValue || (rawLabel as any).key : null) || col.field.charAt(0).toUpperCase() + col.field.slice(1).replace(/_/g, ' ');
+              const rawHeader = resolveColumnLabel(col.label) || col.field.charAt(0).toUpperCase() + col.field.slice(1).replace(/_/g, ' ');
               const header = schema.objectName ? resolveFieldLabel(schema.objectName, col.field, rawHeader) : rawHeader;
 
               // Build custom cell renderer based on column configuration