feat(excel): 优化Excel导入功能支持动态工作表查找

- 添加findSheetIndex方法支持根据工作表名称查找索引
- 实现精确匹配、前缀匹配和包含匹配的查找逻辑
- 在各个控制器中使用动态工作表索引替换固定索引
- 优化CreditCompanyController中的必填字段验证逻辑
- 移除对code字段的必填验证要求
- 添加工作表名称标准化处理功能

src/main/java/com/gxwebsoft/credit/controller/CreditCustomerController.java

@@ -137,8 +137,9 @@ public class CreditCustomerController extends BaseController {
         int successCount = 0;
 
         try {
+            int sheetIndex = ExcelImportSupport.findSheetIndex(file, "客户", 4);
             ExcelImportSupport.ImportResult<CreditCustomerImportParam> importResult = ExcelImportSupport.read(
-                file, CreditCustomerImportParam.class, this::isEmptyImportRow,4);
+                file, CreditCustomerImportParam.class, this::isEmptyImportRow, sheetIndex);
             List<CreditCustomerImportParam> list = importResult.getData();
             int usedTitleRows = importResult.getTitleRows();
             int usedHeadRows = importResult.getHeadRows();