merge(stock-count): CSV 匯出（依賴 F1）併入版本分支 7.2.0.4

src/modules/stock-count.ts

@@ -33,3 +33,10 @@ export interface StockCountReportRow {
  * @returns 逐物料的差異報表列
  */
 export const buildReport = (diffs: StockCountDiff[]): StockCountReportRow[] => diffs.map((diff) => ({ materialId: diff.materialId, diff: diffQty(diff) }));
+
+/**
+ * 將差異報表列轉為 CSV 字串（依賴 F1 的報表列型別）
+ * @param rows - 差異報表列
+ * @returns 以換行分隔的 CSV 內容
+ */
+export const toCsv = (rows: StockCountReportRow[]): string => rows.map((row) => `${row.materialId},${row.diff}`).join("\n");