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/composables/workbenchAiMode/useWorkbenchAiFilePreview.js

@@ -1,5 +1,13 @@
 import { computed, onBeforeUnmount, ref, watch } from 'vue'
 import { buildSelectedFileCards } from './workbenchAiComposerModel.js'
+import { fetchReceiptFolderAsset } from '../../services/receiptFolder.js'
+import {
+  inferPreviewKindFromBlob,
+  inferPreviewKindFromFile,
+  isInlinePreviewUrl,
+  isTemporaryPreviewUrl,
+  resolveDocumentPreviewAsset
+} from '../../utils/documentPreviewAssets.js'
 
 function normalizePreviewText(value) {
   return String(value ?? '').replace(/\s+/g, ' ').trim()
@@ -40,10 +48,6 @@ function normalizePreviewField(field = {}) {
   }
 }
 
-function resolveDocumentPreviewUrl(document = null) {
-  return normalizePreviewText(document?.preview_data_url || document?.previewDataUrl)
-}
-
 function resolveSourceKind(sourceUrl, rawFile = {}) {
   const type = normalizePreviewText(rawFile?.type).toLowerCase()
   const name = normalizePreviewText(rawFile?.name).toLowerCase()
@@ -72,8 +76,18 @@ export function useWorkbenchAiFilePreview({
   scrollInlineConversationToBottom,
   selectedFiles
 }) {
-  const filePreviewState = ref({ open: false, key: '', objectUrl: '' })
-  const selectedFileCards = computed(() => buildSelectedFileCards(selectedFiles.value).map((card, index) => ({
+  const filePreviewState = ref({
+    open: false,
+    key: '',
+    objectUrl: '',
+    objectKind: '',
+    objectSource: '',
+    loading: false
+  })
+  const selectedFileCards = computed(() => buildSelectedFileCards(
+    selectedFiles.value,
+    (file) => attachmentFlow.resolveAiModeReceiptRecognitionState(file)
+  ).map((card, index) => ({
     ...card,
     ocrState: attachmentFlow.resolveAiModeReceiptRecognitionState(selectedFiles.value[index])
   })))
@@ -97,22 +111,94 @@ export function useWorkbenchAiFilePreview({
     }
   }
 
+  function resolveTargetDocument(target) {
+    if (!target?.rawFile) {
+      return null
+    }
+    const recognitionState = attachmentFlow.resolveAiModeReceiptRecognitionState(target.rawFile) || target.card.ocrState || null
+    return recognitionState?.document || null
+  }
+
+  function resolveRemotePreviewAsset(target) {
+    const asset = resolveDocumentPreviewAsset(resolveTargetDocument(target))
+    if (!asset?.url || isInlinePreviewUrl(asset.url) || isTemporaryPreviewUrl(asset.url)) {
+      return null
+    }
+    return asset
+  }
+
+  async function loadRemotePreviewAsset(fileKey) {
+    const target = findSelectedFile(fileKey)
+    const asset = resolveRemotePreviewAsset(target)
+    if (!target?.rawFile || !asset?.url) {
+      return
+    }
+
+    try {
+      const blob = await fetchReceiptFolderAsset(asset.url)
+      const objectUrl = createObjectUrl(blob)
+      const objectKind = inferPreviewKindFromBlob(blob) || asset.kind
+      if (!objectUrl || !['image', 'pdf'].includes(objectKind)) {
+        return
+      }
+      if (!filePreviewState.value.open || filePreviewState.value.key !== fileKey) {
+        URL.revokeObjectURL(objectUrl)
+        return
+      }
+      clearFilePreviewObjectUrl()
+      filePreviewState.value = {
+        ...filePreviewState.value,
+        objectUrl,
+        objectKind,
+        objectSource: asset.source,
+        loading: false
+      }
+    } catch (error) {
+      console.warn('AI mode remote attachment preview unavailable:', error)
+      if (!filePreviewState.value.open || filePreviewState.value.key !== fileKey) {
+        return
+      }
+      clearFilePreviewObjectUrl()
+      filePreviewState.value = {
+        ...filePreviewState.value,
+        objectUrl: createObjectUrl(target.rawFile),
+        objectKind: inferPreviewKindFromFile(target.rawFile),
+        objectSource: 'file',
+        loading: false
+      }
+    }
+  }
+
   function openAiModeFilePreview(fileKey) {
     const target = findSelectedFile(fileKey)
     if (!target?.rawFile) {
       return
     }
     clearFilePreviewObjectUrl()
+    const remoteAsset = resolveRemotePreviewAsset(target)
     filePreviewState.value = {
       open: true,
       key: fileKey,
-      objectUrl: createObjectUrl(target.rawFile)
+      objectUrl: remoteAsset ? '' : createObjectUrl(target.rawFile),
+      objectKind: remoteAsset ? '' : inferPreviewKindFromFile(target.rawFile),
+      objectSource: remoteAsset ? remoteAsset.source : 'file',
+      loading: Boolean(remoteAsset)
+    }
+    if (remoteAsset) {
+      void loadRemotePreviewAsset(fileKey)
     }
   }
 
   function closeAiModeFilePreview() {
     clearFilePreviewObjectUrl()
-    filePreviewState.value = { open: false, key: '', objectUrl: '' }
+    filePreviewState.value = {
+      open: false,
+      key: '',
+      objectUrl: '',
+      objectKind: '',
+      objectSource: '',
+      loading: false
+    }
   }
 
   const activeAiModeFilePreview = computed(() => {
@@ -128,9 +214,16 @@ export function useWorkbenchAiFilePreview({
     const document = recognitionState?.document || null
     const documentFields = Array.isArray(document?.document_fields) ? document.document_fields : document?.fields || []
     const ocrFields = documentFields.map((field) => normalizePreviewField(field)).filter(Boolean)
-    const documentPreviewUrl = resolveDocumentPreviewUrl(document)
-    const sourceUrl = documentPreviewUrl || filePreviewState.value.objectUrl
-    const sourceKind = documentPreviewUrl ? 'image' : resolveSourceKind(sourceUrl, rawFile)
+    const documentPreviewAsset = resolveDocumentPreviewAsset(document)
+    const inlinePreviewAvailable = documentPreviewAsset?.url && isInlinePreviewUrl(documentPreviewAsset.url)
+    const sourceUrl = inlinePreviewAvailable
+      ? documentPreviewAsset.url
+      : filePreviewState.value.objectUrl
+    const sourceKind = inlinePreviewAvailable
+      ? documentPreviewAsset.kind
+      : filePreviewState.value.loading
+        ? 'loading'
+        : filePreviewState.value.objectKind || resolveSourceKind(sourceUrl, rawFile)
     const documentTypeLabel = normalizePreviewText(
       document?.document_type_label ||
         document?.scene_label ||