style(react-flow): 调整节点样式与框选交互

1. 给分组节点添加圆角样式
2. 框选激活时隐藏节点顶部操作栏避免误触发
3. 修复文件末尾换行问题

src/app/globals.css

@@ -97,7 +97,9 @@ body {
 
 .react-flow__node-group {
   padding: 0 !important;
+  border-radius: 12px !important;
 }
+
 /* Larger invisible hit area for easier clicking, especially when zoomed out */
 .react-flow__handle::before {
   content: "";
@@ -249,6 +251,11 @@ body {
   pointer-events: none !important;
 }
 
+/* Box selection should select nodes without opening each node's own action bar. */
+.box-selection-active .react-flow__node.selected .nodrag.nopan.absolute[class*="-top-"] {
+  display: none !important;
+}
+
 /* Edge pulse animation for loading connectors */
 @keyframes flowPulse {
   0% {
@@ -288,4 +295,4 @@ body {
 
 .animate-fan-exit {
   animation: fanExit 0.15s ease-in forwards;
-}
+}