fix: improve formatting and add JSON validation in McpServersDialog

--bug=1060753 --user=刘瑞斌 【应用】AI对话节点的MCP使用自定义方式，配置格式错误依然可以保存成功 https://www.tapd.cn/62980211/s/1760128

ui/src/views/application/component/McpServersDialog.vue

@@ -96,9 +96,9 @@
   </el-dialog>
 </template>
 <script setup lang="ts">
-import { computed, inject, onMounted, ref, watch } from 'vue'
+import {ref, watch} from 'vue'
-import { loadSharedApi } from '@/utils/dynamics-api/shared-api.ts'
+import {MsgError} from "@/utils/message.ts";
-import { useRoute } from 'vue-router'
+import {t} from "@/locales";
 
 const emit = defineEmits(['refresh'])
 
@@ -153,6 +153,12 @@ const open = (data: any, selectOptions: any) => {
 const submit = () => {
   paramFormRef.value.validate((valid: any) => {
     if (valid) {
+      try {
+        JSON.parse(form.value.mcp_servers)
+      } catch (e) {
+        MsgError(t('views.applicationWorkflow.nodes.mcpNode.mcpServerTip'))
+        return
+      }
       emit('refresh', form.value)
       dialogVisible.value = false
     }