fix(form): 表单设计器上传字段点击无反应——label 内 Button 换非交互 span

与 hall 仓 4243a5f 同款：label 的点击转发对交互式后代（原生 <button>）
不生效，文件选择框永不弹出；改 <span class="dyn-file-btn-inner"> 恢复
label→input 原生转发，样式对齐 iview small button。

src/components/DynamicForm.vue

@@ -186,6 +186,7 @@ async function uploadFile(field: Field, ev: Event) {
                                 "
                             >移除</a>
                         </div>
+                        <!-- label 的点击转发对交互式后代（原生 <button>）不生效，内层必须是非交互元素，否则点上传无反应 -->
                         <label class="dyn-file-btn">
                             <input
                                 type="file"
@@ -193,9 +194,10 @@ async function uploadFile(field: Field, ev: Event) {
                                 :accept="field.accept || (field.type === 'image' ? '.jpg,.jpeg,.png,.gif' : '')"
                                 @change="uploadFile(field, $event)"
                             />
-                            <Button size="small" icon="ios-cloud-upload-outline">
+                            <span class="dyn-file-btn-inner">
+                                <Icon type="ios-cloud-upload-outline" />
                                 {{ field.type === 'image' ? '上传图片' : '上传附件' }}
-                            </Button>
+                            </span>
                         </label>
                     </div>
                 </template>
@@ -252,4 +254,28 @@ async function uploadFile(field: Field, ev: Event) {
     margin-right: 8px;
     border-radius: 4px;
 }
+.dyn-file-btn {
+    display: inline-block;
+    cursor: pointer;
+}
+.dyn-file-btn-inner {
+    display: inline-flex;
+    align-items: center;
+    gap: 4px;
+    padding: 0 7px;
+    border: 1px solid #dcdee2;
+    border-radius: 4px;
+    background: #fff;
+    color: #515a6e;
+    font-size: 12px;
+    line-height: 26px;
+    cursor: pointer;
+    user-select: none;
+    transition: color 0.2s, border-color 0.2s;
+}
+.dyn-file-btn:hover .dyn-file-btn-inner {
+    color: #2d8cf0;
+    border-color: #2d8cf0;
+}
+
 </style>