feat(iit): Initialize IIT Manager Agent MVP - Day 1 complete

- Add iit_schema with 5 tables
- Create module structure and types (223 lines)
- WeChat integration verified (Access Token success)
- Update system docs to v2.4
- Add REDCap source folders to .gitignore
- Day 1/14 complete (11/11 tasks)

backend/src/index.ts

@@ -123,6 +123,13 @@ logger.info('✅ ASL智能文献筛选路由已注册: /api/v1/asl');
 await registerDCRoutes(fastify);
 logger.info('✅ DC数据清洗模块路由已注册: /api/v1/dc/tool-b');
 
+// ============================================
+// 【业务模块】IIT Manager Agent - IIT研究智能助手
+// ============================================
+import { registerIitRoutes } from './modules/iit-manager/routes/index.js';
+await registerIitRoutes(fastify);
+logger.info('✅ IIT Manager Agent路由已注册: /api/v1/iit');
+
 // 启动服务器
 const start = async () => {
   try {