feat(iit-manager): Integrate Dify knowledge base for hybrid retrieval

Completed features:
- Created Dify dataset (Dify_test0102) with 2 processed documents
- Linked test0102 project with Dify dataset ID
- Extended intent detection to recognize query_protocol intent
- Implemented queryDifyKnowledge method (semantic search Top 5)
- Integrated hybrid retrieval (REDCap data + Dify documents)
- Fixed AI hallucination bugs (intent detection + API field path)
- Developed debugging scripts
- Completed end-to-end testing (5 scenarios passed)
- Generated comprehensive documentation (600+ lines)
- Updated development plans and module status

Technical highlights:
- Single project single knowledge base architecture
- Smart routing based on user intent
- Prevent AI hallucination by injecting real data/documents
- Session memory for multi-turn conversations
- Reused LLMFactory for DeepSeek-V3 integration

Bug fixes:
- Fixed intent detection missing keywords
- Fixed Dify API response field path error

Testing: All scenarios verified in WeChat production environment

Status: Fully tested and deployed

backend/src/modules/iit-manager/check-iit-table-structure.ts

@@ -0,0 +1,105 @@
+/**
+ * 直接查询数据库中的iit_schema.projects表结构
+ */
+
+import { PrismaClient } from '@prisma/client';
+
+const prisma = new PrismaClient();
+
+async function checkTableStructure() {
+  try {
+    console.log('🔍 查询 iit_schema.projects 表结构...\n');
+
+    // 1. 查询表的所有列信息
+    const columns = await prisma.$queryRaw<any[]>`
+      SELECT 
+        column_name,
+        data_type,
+        character_maximum_length,
+        is_nullable,
+        column_default
+      FROM information_schema.columns
+      WHERE table_schema = 'iit_schema'
+        AND table_name = 'projects'
+      ORDER BY ordinal_position
+    `;
+
+    console.log('📋 表结构：');
+    console.log('='.repeat(100));
+    console.log(
+      'Column Name'.padEnd(30) +
+      'Data Type'.padEnd(20) +
+      'Nullable'.padEnd(12) +
+      'Default'
+    );
+    console.log('='.repeat(100));
+
+    columns.forEach(col => {
+      const colName = col.column_name.padEnd(30);
+      const dataType = (col.data_type + 
+        (col.character_maximum_length ? `(${col.character_maximum_length})` : '')
+      ).padEnd(20);
+      const nullable = (col.is_nullable === 'YES' ? 'YES' : 'NO').padEnd(12);
+      const defaultVal = col.column_default || '';
+      
+      console.log(`${colName}${dataType}${nullable}${defaultVal}`);
+    });
+
+    console.log('='.repeat(100));
+    console.log(`\n总计: ${columns.length} 个字段\n`);
+
+    // 2. 检查是否存在 dify 相关字段
+    const difyColumns = columns.filter(col => 
+      col.column_name.toLowerCase().includes('dify')
+    );
+
+    if (difyColumns.length > 0) {
+      console.log('✅ 找到Dify相关字段：');
+      difyColumns.forEach(col => {
+        console.log(`   - ${col.column_name} (${col.data_type}, nullable: ${col.is_nullable})`);
+      });
+    } else {
+      console.log('❌ 未找到Dify相关字段');
+    }
+    console.log('');
+
+    // 3. 查询test0102项目的当前数据
+    console.log('📊 查询test0102项目的当前配置...\n');
+    const projects = await prisma.$queryRaw<any[]>`
+      SELECT 
+        id,
+        name,
+        redcap_project_id,
+        redcap_url,
+        dify_dataset_id,
+        status,
+        created_at
+      FROM iit_schema.projects
+      WHERE redcap_project_id = '16'
+    `;
+
+    if (projects.length > 0) {
+      console.log('✅ test0102项目信息：');
+      const project = projects[0];
+      console.log(`   ID: ${project.id}`);
+      console.log(`   名称: ${project.name}`);
+      console.log(`   REDCap项目ID: ${project.redcap_project_id}`);
+      console.log(`   REDCap URL: ${project.redcap_url}`);
+      console.log(`   Dify Dataset ID: ${project.dify_dataset_id || '(未设置)'}`);
+      console.log(`   状态: ${project.status}`);
+      console.log(`   创建时间: ${project.created_at}`);
+    } else {
+      console.log('❌ 未找到test0102项目');
+    }
+
+    console.log('');
+
+  } catch (error) {
+    console.error('❌ 查询失败:', error);
+  } finally {
+    await prisma.$disconnect();
+  }
+}
+
+checkTableStructure();
+