🐛 fix(connectionStore): 修复分组连接时树节点的更新逻辑

确保连接到分组中的连接时，原地更新现有节点属性，避免添加重复的根节点。

使用 findNode 递归搜索替代 findIndex 只搜索根级别。原地修改节点属性而非替换整个对象，保留父子引用关系。

apps/desktop/src/stores/connectionStore.ts

@@ -759,19 +759,21 @@ export const useConnectionStore = defineStore("connection", () => {
       clearConnectionError(config.id);
       if (id !== config.id) clearConnectionError(id);
 
-      const node: TreeNode = {
-        id,
-        label: config.name,
-        type: "connection",
-        connectionId: id,
-        isExpanded: false,
-        children: [],
-      };
-      const existing = treeNodes.value.findIndex((n) => n.id === id);
-      if (existing >= 0) {
-        treeNodes.value[existing] = node;
+      const existing = findNode(treeNodes.value, id);
+      if (existing) {
+        existing.label = config.name;
+        existing.type = "connection";
+        existing.connectionId = id;
+        existing.children = existing.children || [];
       } else {
-        treeNodes.value.push(node);
+        treeNodes.value.push({
+          id,
+          label: config.name,
+          type: "connection",
+          connectionId: id,
+          isExpanded: false,
+          children: [],
+        });
       }
       return id;
     } catch (e) {