fix(credit): 修复债务人公司ID匹配逻辑

- 将默认更新条件从 companyId 为空改为 companyId=0
- 修改查询条件从 isNull 改为等于 0 的判断
- 更新业务逻辑中对 needUpdate 的判断条件

docs(shop): 添加经销商推荐绑定接口文档

- 新增 SHOP_DEALER_REFEREE_BINDING.md 文档
- 定义 POST /api/shop/shop-dealer-referee 接口规则
- 说明邀请人有效性验证和防止自绑限制
- 描述首次绑定幂等性和溯源字段要求
- 提供数据库唯一索引建议和建表语句

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

@@ -151,7 +151,7 @@ public class CreditJudgmentDebtorController extends BaseController {
     /**
      * 根据企业名称匹配企业并更新 companyId（匹配 CreditCompany.name / CreditCompany.matchName）
      *
-     * <p>默认仅更新 companyId 为空的记录；如需覆盖更新，传 onlyNull=false。</p>
+     * <p>默认仅更新 companyId=0 的记录；如需覆盖更新，传 onlyNull=false。</p>
      */
     @PreAuthorize("hasAuthority('credit:creditJudgmentDebtor:update')")
     @OperationLog
@@ -170,7 +170,7 @@ public class CreditJudgmentDebtorController extends BaseController {
             .eq(currentTenantId != null, CreditJudgmentDebtor::getTenantId, currentTenantId)
             .isNotNull(CreditJudgmentDebtor::getName);
         if (Boolean.TRUE.equals(onlyNull)) {
-            debtorQuery.isNull(CreditJudgmentDebtor::getCompanyId);
+            debtorQuery.eq(CreditJudgmentDebtor::getCompanyId, 0);
         }
         if (limit != null && limit > 0) {
             debtorQuery.last("limit " + Math.min(limit, 200000));
@@ -269,7 +269,7 @@ public class CreditJudgmentDebtorController extends BaseController {
 
                 boolean needUpdate = d.getCompanyId() == null || !companyId.equals(d.getCompanyId());
                 if (Boolean.TRUE.equals(onlyNull)) {
-                    needUpdate = d.getCompanyId() == null;
+                    needUpdate = d.getCompanyId() != null && d.getCompanyId() == 0;
                 }
                 if (!needUpdate) {
                     continue;