feat(ui): 为可伸缩弹窗新增额外按钮插槽并调整可折叠面板边距

- 在 `StretchableModal` 头部新增名为 `extraButtons` 的插槽，用于放置附加控制组件
- 确保 `StretchableModal` 始终渲染底部插槽（footer slot），移除条件显示逻辑
- 调整 `CollapsiblePanel` 的下边距（margin-bottom），使其仅在非最后一个子元素时生效，从而消除末尾的冗余空间
- 为额外按钮区域添加悬停发光效果样式

packages/screen/src/views/3DSituationalAwarenessRefactor/components/shared/CollapsiblePanel.vue

@@ -160,7 +160,9 @@ function onAfterLeave(el) {
 .collapsible-panel {
   display: flex;
   flex-direction: column;
-  margin-bottom: vh(17);
+  &:not(:last-child) {
+    margin-bottom: vh(17);
+  }
   border: 2px solid transparent; /* 防止 hover 时抖动 */
 
   &__header {

packages/screen/src/views/3DSituationalAwarenessRefactor/components/shared/StretchableModal.vue

@@ -15,6 +15,9 @@
           <div class="stretchable-modal__header">
             <slot name="header">
               <h3 class="stretchable-modal__title">{{ title }}</h3>
+              <div class="stretchable-modal__extra">
+                <slot name="extraButtons"></slot>
+              </div>
             </slot>
             <button
               v-if="showClose"
@@ -36,7 +39,7 @@
           </div>
 
           <!-- 底部：大弹窗bottom切图.png -->
-          <div v-if="$slots.footer" class="stretchable-modal__footer">
+          <div class="stretchable-modal__footer">
             <slot name="footer"></slot>
           </div>
         </div>
@@ -212,6 +215,20 @@ onUnmounted(() => {
     margin: 0;
   }
 
+  &__extra {
+    position: absolute;
+    right: 125px;
+    top: 18px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    &:hover {
+    // border: 2px solid rgba(255, 80, 80, 0.6);
+    box-shadow: 0 0 10px rgba(255, 80, 80, 0.6), 0 0 20px rgba(255, 0, 0, 0.4),
+      0 0 35px rgba(255, 0, 0, 0.25);
+  }
+  }
+
   &__close {
     position: absolute;
     top: 34px;