feat(frontend): add UUID column to material management table

- Add UUID field extraction in backend /getFiles endpoint
- Extract UUID from file_path (first part before underscore)
- Add UUID column to material management table in frontend
- Set appropriate width for UUID column display
- Maintain data consistency between backend and frontend

sau_frontend/src/views/MaterialManagement.vue

@@ -25,6 +25,7 @@
       
       <div v-if="filteredMaterials.length > 0" class="material-list">
         <el-table :data="filteredMaterials" style="width: 100%">
+          <el-table-column prop="uuid" label="UUID" width="180" />
           <el-table-column prop="filename" label="文件名" width="300" />
           <el-table-column prop="filesize" label="文件大小" width="120">
             <template #default="scope">