fix: 证书批量导入改为覆盖式回填 (直接替换旧 URL, 不再逗号追加)

Co-Authored-By: Claude Code <noreply@anthropic.com>

ry-api/ruoyi-business/src/main/java/com/ruoyi/business/service/impl/BizExpertServiceImpl.java

@@ -526,8 +526,6 @@ public class BizExpertServiceImpl implements IBizExpertService
 
         int updated = 0;
         int processed = 0;
-        // expertId -> 已拼接的 URL (处理同一专家多文件时避免互相覆盖)
-        Map<Long, String> accumulated = new HashMap<>();
         List<Map<String, Object>> results = new ArrayList<>();
         for (CertFile f : files) {
             processed++;
@@ -544,17 +542,13 @@ public class BizExpertServiceImpl implements IBizExpertService
             BizExpert matched = cm.expert;
 
             String url = ossUploader.uploadWithOriginalName(f.bytes, f.name, subDir);
-            String existing = accumulated.containsKey(matched.getExpertId())
-                    ? accumulated.get(matched.getExpertId())
-                    : (practice ? matched.getPracticeCertUrl() : matched.getTitleCertUrl());
-            String joined = (existing == null || existing.isEmpty()) ? url : existing + "," + url;
-            accumulated.put(matched.getExpertId(), joined);
 
+            // 覆盖式回填: 直接替换为新 URL (证书不允许多张)
             BizExpert entity = new BizExpert();
             entity.setExpertId(matched.getExpertId());
             entity.setUpdateBy(username);
-            if (practice) entity.setPracticeCertUrl(joined);
-            else entity.setTitleCertUrl(joined);
+            if (practice) entity.setPracticeCertUrl(url);
+            else entity.setTitleCertUrl(url);
             bizExpertMapper.updateByPrimaryKey(entity);
             updated++;