Fix: Resolve array mutation bug preventing Grid sorting from working

- Changed result.sort() to result = [...result].sort() to create new array reference
- React now properly detects changes and re-renders sorted data
- All columns (Sell Out, Units, S.O. Δ%, Units Δ%) now sort correctly
- Verified with comprehensive browser testing

components/DataGrid.tsx

@@ -334,7 +334,8 @@ const DataGrid: React.FC<DataGridProps> = ({ data }) => {
 
         // 2. Sort
         if (sortConfig.key) {
-            result.sort((a, b) => {
+            // Create a copy to avoid mutating the original array and ensure React detects the change
+            result = [...result].sort((a, b) => {
                 let valA: number | string = '';
                 let valB: number | string = '';