样式微调，冗余代码清理

src/components/composer/flow/ComposerButtons.vue

@@ -1,7 +1,13 @@
 <template>
   <div class="composer-buttons">
     <div class="right-buttons">
-      <q-btn icon="close" dense flat v-close-popup v-if="showCloseButton">
+      <q-btn
+        icon="close"
+        dense
+        flat
+        v-if="showCloseButton"
+        @click="$emit('action', 'close')"
+      >
         <q-tooltip>退出可视化编排</q-tooltip>
       </q-btn>
       <q-btn

src/components/composer/flow/DropArea.vue

@@ -48,13 +48,16 @@ export default defineComponent({
   justify-content: center;
   border: 2px dashed #e0e0e0;
   border-radius: 4px;
-  margin: 8px 0;
   transition: all 0.3s ease;
   flex: 1;
   user-select: none;
   transition: all 0.3s ease;
 }
 
+.drop-area:has(.add-area) {
+  margin: 8px 0;
+}
+
 .body--dark .drop-area {
   border-color: #676666;
 }
@@ -94,7 +97,7 @@ export default defineComponent({
   display: flex;
   align-items: center;
   justify-content: center;
-  color: grey
+  color: grey;
 }
 
 .add-area {