feat(group): 添加 MCP XML 注入开关

- Group 新增 mcp_xml_inject 字段，控制 Antigravity 平台的 MCP XML 协议注入
- 默认启用，可在分组设置中关闭
- 修复 GetByKeyForAuth 遗漏查询 mcp_xml_inject 字段导致认证缓存值始终为 false 的问题

frontend/src/i18n/locales/en.ts

@@ -943,6 +943,12 @@ export default {
         noRulesHint: 'Add routing rules to route specific model requests to designated accounts',
         searchAccountPlaceholder: 'Search accounts...',
         accountsHint: 'Select accounts to prioritize for this model pattern'
+      },
+      mcpXml: {
+        title: 'MCP XML Protocol Injection',
+        tooltip: 'When enabled, if the request contains MCP tools, an XML format call protocol prompt will be injected into the system prompt. Disable this to avoid interference with certain clients.',
+        enabled: 'Enabled',
+        disabled: 'Disabled'
       }
     },