fix: 优化文件上传对话框布局

- 调整顶部导航按钮位置
- 隐藏对话框默认关闭按钮
- 优化文件上传流程交互

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/views/Knowledge.vue

@@ -863,15 +863,12 @@ const deleteDocument = async (docId: string) => {
       width="calc(100vw - 40px)"
       top="20px"
       :close-on-click-modal="false"
+      :show-close="false"
       class="kb-dialog file-upload-dialog"
     >
       <div class="file-upload-layout">
         <!-- 顶部导航 -->
         <div class="file-header">
-          <button class="back-btn" @click="showFileUploadDialog = false">
-            <i class="fa-solid fa-arrow-left"></i>
-          </button>
-          <h2 class="file-title">{{ selectedKnowledge?.name || 'Knowledge Base' }}</h2>
           <input
             type="file"
             ref="fileInput"
@@ -883,6 +880,10 @@ const deleteDocument = async (docId: string) => {
             <i class="fa-solid fa-upload"></i>
             Upload
           </button>
+          <h2 class="file-title">{{ selectedKnowledge?.name || 'Knowledge Base' }}</h2>
+          <button class="back-btn" @click="showFileUploadDialog = false">
+            <i class="fa-solid fa-xmark"></i>
+          </button>
         </div>
 
         <!-- 标签栏 -->

web/src/views/knowledge/knowledge.css

@@ -645,6 +645,8 @@
 }
 
 .file-title {
+  flex: 1;
+  text-align: center;
   font-size: 16px;
   font-weight: 600;
   color: #ffffff;