修复下拉框弹出容器：添加类型定义和回退逻辑

Author: funnywwh

frontend/src/views/requirement/Requirement.vue

@@ -497,15 +497,15 @@
             :multiple="false"
             placeholder="选择指派给"
             :show-role="true"
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           />
         </a-form-item>
         <a-form-item label="状态" name="status">
           <a-select
             v-model:value="assignFormData.status"
             placeholder="选择状态（可选，不选择则自动修改）"
             allow-clear
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           >
             <a-select-option value="draft">草稿</a-select-option>
             <a-select-option value="reviewing">评审中</a-select-option>

frontend/src/views/requirement/RequirementDetail.vue

@@ -168,15 +168,15 @@
             :multiple="false"
             placeholder="选择指派给"
             :show-role="true"
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           />
         </a-form-item>
         <a-form-item label="状态" name="status">
           <a-select
             v-model:value="assignFormData.status"
             placeholder="选择状态（可选，不选择则自动修改）"
             allow-clear
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           >
             <a-select-option value="draft">草稿</a-select-option>
             <a-select-option value="reviewing">评审中</a-select-option>

frontend/src/views/task/Task.vue

@@ -590,15 +590,15 @@
             :multiple="false"
             placeholder="选择指派给"
             :show-role="true"
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           />
         </a-form-item>
         <a-form-item label="状态" name="status">
           <a-select
             v-model:value="assignFormData.status"
             placeholder="选择状态（可选，不选择则自动修改）"
             allow-clear
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           >
             <a-select-option value="wait">未开始</a-select-option>
             <a-select-option value="doing">进行中</a-select-option>

frontend/src/views/task/TaskDetail.vue

@@ -297,15 +297,15 @@
             :multiple="false"
             placeholder="选择指派给"
             :show-role="true"
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           />
         </a-form-item>
         <a-form-item label="状态" name="status">
           <a-select
             v-model:value="assignFormData.status"
             placeholder="选择状态（可选，不选择则自动修改）"
             allow-clear
-            :get-popup-container="(triggerNode) => triggerNode.parentElement"
+            :get-popup-container="(triggerNode: HTMLElement) => triggerNode.parentElement || triggerNode.ownerDocument.body"
           >
             <a-select-option value="wait">未开始</a-select-option>
             <a-select-option value="doing">进行中</a-select-option>