Preserve QExcell sheet dimensions in XLSX

src/types.ts

@@ -22,6 +22,8 @@ export interface Sheet {
   frozenPane?: SheetFrozenPane;
   autoFilter?: string;
   tabColor?: string;
+  columnWidths?: Record<string, number>;
+  rowHeights?: Record<string, number>;
   cells: Record<string, string>;
   mergedCells?: MergedCellRange[];
   hyperlinks?: Record<string, string>;