修复前后端显示异常问题（受试者、中心、负责人、日期等）

frontend/src/views/admin/AuditLogs.vue

@@ -44,14 +44,19 @@
         </el-button>
       </div>
       <el-table :data="logs" v-loading="loading" style="width: 100%">
-        <el-table-column prop="timestamp" label="时间" width="180" />
+        <el-table-column prop="timestamp" label="时间" width="180">
+          <template #default="scope">{{ displayDateTime(scope.row.timestamp) }}</template>
+        </el-table-column>
         <el-table-column prop="actorName" label="操作人" width="140" />
         <el-table-column prop="actorRoleLabel" label="角色" width="120" />
         <el-table-column prop="eventLabel" label="操作类型" min-width="160" />
         <el-table-column prop="actionText" label="操作内容" min-width="180" />
         <el-table-column label="操作对象" min-width="180">
           <template #default="scope">
-            {{ scope.row.targetTypeLabel }}（{{ scope.row.targetId }} {{ scope.row.targetName || "" }}）
+            <span v-if="scope.row.targetTypeLabel">
+              {{ scope.row.targetTypeLabel }}（{{ scope.row.targetName || "—" }}）
+            </span>
+            <span v-else>—</span>
           </template>
         </el-table-column>
         <el-table-column label="变更详情" min-width="220">
@@ -94,6 +99,7 @@ import { useAuthStore } from "../../store/auth";
 import { roleDict, getDictLabel } from "../../dictionaries";
 import { exportAuditCsv } from "../../audit/export/auditExportService";
 import { logAudit } from "../../audit";
+import { displayDateTime } from "../../utils/display";
 
 const study = useStudyStore();
 const auth = useAuthStore();