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/tests/receipt-folder-view.test.mjs

@@ -62,6 +62,15 @@ function testReceiptFolderViewSurface() {
   assert.doesNotMatch(view, /const claims = await fetchExpenseClaims\(\)/)
 }
 
+function testReceiptPreviewKindFollowsReturnedBlobType() {
+  const view = readProjectFile('web/src/views/ReceiptFolderView.vue')
+
+  assert.match(view, /import \{ inferPreviewKindFromBlob \} from '\.\.\/utils\/documentPreviewAssets\.js'/)
+  assert.doesNotMatch(view, /function inferPreviewKindFromBlob\(blob\)/)
+  assert.match(view, /const resolvedPreviewKind = inferPreviewKindFromBlob\(blob\)/)
+  assert.match(view, /preview_kind: resolvedPreviewKind/)
+}
+
 function testReceiptFolderServiceContract() {
   const service = readProjectFile('web/src/services/receiptFolder.js')
   const ocrService = readProjectFile('web/src/services/ocr.js')
@@ -180,6 +189,7 @@ function testAssistantUnlinkedReceiptPrompt() {
 
 function run() {
   testReceiptFolderViewSurface()
+  testReceiptPreviewKindFollowsReturnedBlobType()
   testReceiptFolderServiceContract()
   testAppShellWiresReceiptFolder()
   testSharedDocumentListStyleReuse()