feat: 前端集成更新材料功能和PDF预览

- 列表页添加更新材料按钮（更多操作中）
- 添加updateFiles API接口
- 文件归档弹窗添加PDF预览功能

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/views/purchase/purchasingrequisition/FileArchiveDialog.vue

@@ -32,7 +32,7 @@
       class="file-table"
     >
       <el-table-column type="index" label="序号" width="60" align="center" />
-      <el-table-column prop="fileTitle" label="文件名称" min-width="250" show-overflow-tooltip>
+      <el-table-column prop="fileTitle" label="文件名称" min-width="220" show-overflow-tooltip>
         <template #default="{ row }">
           <div class="file-name">
             <el-icon class="file-icon"><Document /></el-icon>
@@ -40,13 +40,21 @@
           </div>
         </template>
       </el-table-column>
-      <el-table-column prop="fileTypeDesc" label="文件类型" width="180" align="center">
+      <el-table-column prop="fileTypeDesc" label="文件类型" width="160" align="center">
         <template #default="{ row }">
           <el-tag type="info">{{ row.fileTypeDesc || '未知类型' }}</el-tag>
         </template>
       </el-table-column>
-      <el-table-column label="操作" width="100" align="center" fixed="right">
+      <el-table-column label="操作" width="150" align="center" fixed="right">
         <template #default="{ row }">
+          <el-button
+            type="primary"
+            link
+            icon="View"
+            @click="handlePreview(row)"
+          >
+            预览
+          </el-button>
           <el-button
             type="primary"
             link
@@ -67,6 +75,26 @@
       <el-button @click="visible = false">关闭</el-button>
     </template>
   </el-dialog>
+
+  <!-- PDF预览弹窗 -->
+  <el-dialog
+    v-model="previewVisible"
+    title="文件预览"
+    width="90%"
+    top="5vh"
+    destroy-on-close
+    append-to-body
+    class="preview-dialog"
+  >
+    <div class="preview-container">
+      <iframe
+        v-if="previewUrl"
+        :src="previewUrl"
+        class="preview-iframe"
+        frameborder="0"
+      />
+    </div>
+  </el-dialog>
 </template>
 
 <script setup lang="ts">
@@ -87,6 +115,8 @@ interface FileItem {
 const visible = ref(false)
 const loading = ref(false)
 const downloading = ref(false)
+const previewVisible = ref(false)
+const previewUrl = ref('')
 const purchaseId = ref('')
 const purchaseNo = ref('')
 const fileList = ref<FileItem[]>([])
@@ -119,6 +149,29 @@ const loadFileList = async () => {
   }
 }
 
+const isPdfFile = (fileName: string): boolean => {
+  if (!fileName) return false
+  const ext = fileName.toLowerCase().split('.').pop()
+  return ext === 'pdf'
+}
+
+const handlePreview = (row: FileItem) => {
+  if (!row.downloadUrl) {
+    useMessage().warning('文件预览地址不存在')
+    return
+  }
+
+  if (!isPdfFile(row.fileTitle)) {
+    useMessage().info('仅支持PDF格式文件预览，将为您下载文件')
+    handleDownloadFile(row)
+    return
+  }
+
+  // 使用iframe预览PDF（通过后端下载接口获取文件流）
+  previewUrl.value = row.downloadUrl
+  previewVisible.value = true
+}
+
 const handleDownloadFile = (row: FileItem) => {
   if (row.downloadUrl) {
     window.open(row.downloadUrl, '_blank')
@@ -182,4 +235,14 @@ defineExpose({
 .empty-tip {
   padding: 40px 0;
 }
-</style>
+
+.preview-container {
+  width: 100%;
+  height: calc(90vh - 120px);
+}
+
+.preview-iframe {
+  width: 100%;
+  height: 100%;
+}
+</style>