fix(stocking): 修复编辑回填因 attachment 格式导致的车辆明细不渲染

后端 show 返回的 attachment 为 JSON 字符串时，.map 抛 TypeError
中断整个 items 回填。增加 normalizeAttachment 统一兼容
数组/字符串/空值。

Co-Authored-By: Claude <noreply@anthropic.com>

src/composables/useStockingForm.ts

@@ -974,6 +974,20 @@ export function useStockingForm(isFinal = false, stockingId?: string | number) {
   }
 
   // 数据回显方法
+  // 后端 attachment 可能返回数组或 JSON 字符串（未 decode），统一转数组
+  const normalizeAttachment = (raw: any): any[] => {
+    if (Array.isArray(raw)) return raw
+    if (typeof raw === 'string' && raw.trim()) {
+      try {
+        const parsed = JSON.parse(raw)
+        return Array.isArray(parsed) ? parsed : []
+      } catch {
+        return []
+      }
+    }
+    return []
+  }
+
   const populateFromDetail = (res: any) => {
     if (!res) return
     isPopulating.value = true
@@ -1021,7 +1035,7 @@ export function useStockingForm(isFinal = false, stockingId?: string | number) {
       _echo_vin: Boolean(it.vin),
       mileage: it.mileage ?? 0,
       model_snapshot: it.model_snapshot || '',
-      attachment_files: (it.attachment || []).map((f: any) => ({
+      attachment_files: normalizeAttachment(it.attachment).map((f: any) => ({
         name: f.original_name || f.name || '附件',
         url: f.url || f.file_url || '',
         file_name: f.file_name || f.url || ''