refactor(品牌工具页): 抽取 formatDateTime 与 uploadPathsToJava 公共工具

- 新增 shared/utils/datetime.ts：13 个品牌页逐字重复的 formatDateTime 收敛为一处；
  语义不同的 3 个变体（toLocaleString / 字符串切片 / 支持时间戳）保留不动
- 新增 shared/utils/upload-to-java.ts：10 个品牌页的上传循环收敛，api 依赖注入便于单测；
  保留 uploadOss（品牌Tab）与 returnEmptyWhenUnavailable（跟价）两处行为差异
- 补 datetime / upload-to-java 单测 10 例

净减约 327 行；vue-tsc 构建与 690 个前端单测全通过

frontend-vue/src/pages/brand/components/BrandDedupeTab.vue

@@ -120,12 +120,14 @@ import { ElMessage } from 'element-plus'
 import AmazonToolPageShell from '@/pages/amazon/components/AmazonToolPageShell.vue';
 import TaskCenterPanel from '@/shared/components/tasks/TaskCenterPanel.vue'
 import type { TaskItemView, TaskStatCard } from '@/shared/components/tasks/types'
-import { expandBrandFolderRecursive, type BrandExpandFolderItem } from '@/shared/api/brand'
+import { expandBrandFolderRecursive } from '@/shared/api/brand'
 import { deleteDedupeHistory, getDedupeHistory, getDedupeResultDownloadUrl, getDedupeRunProgress, getExcelInfo, runDedupe, type DedupeResultItem, type DedupeRunProgressVo, type DedupeRunVo } from '@/shared/api/java-modules'
 import { getPywebviewApi, type UploadedJavaFile } from '@/shared/bridges/pywebview'
 import { saveUrlWithProgress } from '@/shared/utils/download-progress'
 import { EXCEL_EXTENSIONS, checkSelectedFiles, guardBlocked } from '@/shared/dispatch-guard'
 import { passGuard } from '@/shared/dispatch-guard-ui'
+import { formatDateTime } from '@/shared/utils/datetime'
+import { uploadPathsToJava } from '@/shared/utils/upload-to-java'
 
 const cleanAvailableColumns = ref<string[]>([])
 const cleanSelectedColumns = ref<string[]>([])
@@ -144,19 +146,6 @@ const cleanDisplayPaths = computed(() => cleanSelectedPaths.value.slice(0, 8))
 const latestRunId = ref('')
 const cleanRunStartedAt = ref('')
 
-function formatDateTime(value?: string) {
-  if (!value) return '-'
-  const date = new Date(value)
-  if (Number.isNaN(date.getTime())) return value
-  const year = date.getFullYear()
-  const month = String(date.getMonth() + 1).padStart(2, '0')
-  const day = String(date.getDate()).padStart(2, '0')
-  const hours = String(date.getHours()).padStart(2, '0')
-  const minutes = String(date.getMinutes()).padStart(2, '0')
-  const seconds = String(date.getSeconds()).padStart(2, '0')
-  return `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`
-}
-
 function itemSource(item: TaskItemView): DedupeResultItem {
   return item.source as DedupeResultItem
 }
@@ -231,24 +220,6 @@ function clearAllCleanColumns() {
   cleanSelectedColumns.value = []
 }
 
-async function uploadPathsToJava(paths: Array<string | BrandExpandFolderItem>) {
-  const api = getPywebviewApi()
-  if (!api?.upload_file_to_java) {
-    throw new Error('当前桌面端未提供文件上传桥接能力')
-  }
-  const uploaded: UploadedJavaFile[] = []
-  for (const item of paths) {
-    const filePath = typeof item === 'string' ? item : item.absolutePath
-    const relativePath = typeof item === 'string' ? undefined : item.relativePath
-    const result = await api.upload_file_to_java(filePath, relativePath)
-    if (!result?.success || !result.data) {
-      throw new Error(result?.error || result?.message || `上传失败：${filePath}`)
-    }
-    uploaded.push(result.data)
-  }
-  return uploaded
-}
-
 async function loadCleanHeaders(fileKey: string) {
   const result = await getExcelInfo(fileKey)
   if (!result.headers?.length) {
@@ -272,7 +243,7 @@ async function loadCleanHeaders(fileKey: string) {
 async function handleSelectedPaths(paths: string[], successMessage: string) {
   cleanSelectedPaths.value = paths
   cleanArchiveName.value = ''
-  cleanUploadedFiles.value = await uploadPathsToJava(paths)
+  cleanUploadedFiles.value = await uploadPathsToJava(getPywebviewApi(), paths)
   if (cleanUploadedFiles.value.length > 0) {
     await loadCleanHeaders(cleanUploadedFiles.value[0].fileKey)
   }
@@ -314,7 +285,7 @@ async function selectCleanFolder() {
     if (result.success && result.items?.length) {
       if (!(await passGuard(checkSelectedFiles(result.items, { allowedExtensions: EXCEL_EXTENSIONS })))) return
       cleanSelectedPaths.value = result.items.map((item) => item.relativePath)
-      cleanUploadedFiles.value = await uploadPathsToJava(result.items)
+      cleanUploadedFiles.value = await uploadPathsToJava(getPywebviewApi(), result.items)
       if (cleanUploadedFiles.value.length > 0) {
         await loadCleanHeaders(cleanUploadedFiles.value[0].fileKey)
       }