feat(wecom): 企微 API 插件增加 MCP Streamable HTTP 端点

与 REST/OpenAPI 并存，按实例权限自动 tools/list，免手填工具。

Co-authored-by: Cursor <cursoragent@cursor.com>

server/dukang-api/src/integrations/wecom/wecom-plugin.util.test.ts

@@ -0,0 +1,26 @@
+import { BadRequestException } from '@nestjs/common';
+import { describe, expect, it } from 'vitest';
+import { wecomPluginCaller, wecomPluginMcpErrorText, wecomPluginQueryArg } from './wecom-plugin.util';
+
+describe('wecomPluginCaller', () => {
+  it('prefers X-WeCom-User-Id', () => {
+    expect(wecomPluginCaller({ headers: { 'x-wecom-userid': 'alice', userid: 'bob' } })).toBe('alice');
+  });
+
+  it('falls back to plugin', () => {
+    expect(wecomPluginCaller({ headers: {} })).toBe('plugin');
+  });
+});
+
+describe('wecomPluginMcpErrorText', () => {
+  it('unwraps Nest HttpException message', () => {
+    expect(wecomPluginMcpErrorText(new BadRequestException('请提供查询关键词 q'))).toBe('请提供查询关键词 q');
+  });
+});
+
+describe('wecomPluginQueryArg', () => {
+  it('stringifies numbers and drops empty', () => {
+    expect(wecomPluginQueryArg(2)).toBe('2');
+    expect(wecomPluginQueryArg('  ')).toBeUndefined();
+  });
+});