refactor: add useFileUtils composable for shared file helpers

web/frontend/src/composables/useFileUtils.ts

@@ -0,0 +1,20 @@
+export function statusType(status: string): string {
+  const map: Record<string, string> = {
+    done: 'success', merged: 'success', excel_done: 'warning',
+    ocr_done: 'info', pending: 'info'
+  }
+  return map[status] || 'info'
+}
+
+export function statusText(status: string): string {
+  const map: Record<string, string> = {
+    done: '已完成', merged: '已合并', excel_done: '已处理',
+    ocr_done: '已OCR', pending: '待处理'
+  }
+  return map[status] || status
+}
+
+export function fmtTime(t: string): string {
+  if (!t) return '--'
+  return t.replace('T', ' ').slice(0, 19)
+}