feat(web): 设置中心缓存管理与文件预览资产工具

- 新增 documentPreviewAssets 工具，统一从 URL/Blob/File 推断预览类型（image/pdf/file/unsupported）
- SettingsView/SettingsView.js/settingsModelHelper 新增系统缓存管理区块，调用 /settings/cache/clear 并展示清理结果；useSettings/services 适配
- WorkbenchAiFilePreviewDialog/useWorkbenchAiFilePreview 接入预览资产工具，workbenchAiComposerModel 调整文件处理
- ReceiptFolder/LogDetailView/DigitalEmployeeWorkRecords/travelReimbursementAttachmentModel 配套适配
- 新增 settings-cache-management-section 测试，更新 settings-llm/rendering/receipt-folder-view/composer-components/attachment-association 测试

web/src/components/audit/DigitalEmployeeWorkRecords.vue

@@ -250,10 +250,6 @@
         </template>
 
         <template #actions>
-          <button class="minor-action" type="button" :disabled="!selectedRunDetail?.run_id" @click="openTraceCenter">
-            <i class="mdi mdi-timeline-text-outline"></i>
-            <span>查看 Trace</span>
-          </button>
           <button class="minor-action" type="button" :disabled="detailLoading" @click="reloadSelectedDetail">
             <i class="mdi mdi-refresh"></i>
             <span>{{ detailLoading ? '刷新中...' : '刷新详情' }}</span>
@@ -266,7 +262,6 @@
 
 <script setup>
 import { computed, onBeforeUnmount, onMounted, ref, watch } from 'vue'
-import { useRouter } from 'vue-router'
 
 import AuditPickerFilter from './AuditPickerFilter.vue'
 import DigitalEmployeeRunProducts from './DigitalEmployeeRunProducts.vue'
@@ -303,7 +298,6 @@ const props = defineProps({
 const emit = defineEmits(['summary-change', 'detail-open-change', 'detail-topbar-change'])
 
 const { toast } = useToast()
-const router = useRouter()
 const runs = ref([])
 const loading = ref(false)
 const errorMessage = ref('')
@@ -586,14 +580,6 @@ function closeWorkRecordDetail() {
   detailError.value = ''
 }
 
-function openTraceCenter() {
-  const runId = String(selectedRunDetail.value?.run_id || selectedRunId.value || '').trim()
-  if (!runId) {
-    return
-  }
-  router.push({ name: 'app-settings', query: { section: 'agentTraces', run_id: runId } })
-}
-
 watch(
   () => props.focusRunId,
   (runId) => {

web/src/components/business/workbench-ai/WorkbenchAiFilePreviewDialog.vue

@@ -36,6 +36,10 @@
               class="workbench-ai-file-preview-frame"
               title="附件 PDF 预览"
             ></iframe>
+            <div v-else-if="preview.sourceKind === 'loading'" class="workbench-ai-file-preview-state">
+              <i class="mdi mdi-loading"></i>
+              <span>正在加载统一预览。</span>
+            </div>
             <div v-else class="workbench-ai-file-preview-state">
               <i class="mdi mdi-file-eye-outline"></i>
               <span>当前附件暂不支持直接预览。</span>