feat(iit-manager): Add WeChat Official Account integration for patient notifications

Features:
- PatientWechatCallbackController for URL verification and message handling
- PatientWechatService for template and customer messages
- Support for secure mode (message encryption/decryption)
- Simplified route /wechat/patient/callback for WeChat config
- Event handlers for subscribe/unsubscribe/text messages
- Template message for visit reminders

Technical details:
- Reuse @wecom/crypto for encryption (compatible with Official Account)
- Relaxed Fastify schema validation to prevent early request blocking
- Access token caching (7000s with 5min pre-refresh)
- Comprehensive logging for debugging

Testing: Local URL verification passed, ready for SAE deployment

Status: Code complete, waiting for WeChat platform configuration

backend/src/modules/iit-manager/generate-wechat-tokens.ts

@@ -0,0 +1,167 @@
+/**
+ * 生成微信服务号Token和EncodingAESKey
+ * 
+ * 功能：
+ * 1. 生成符合要求的Token（3-32位）
+ * 2. 生成符合要求的EncodingAESKey（43位）
+ * 3. 输出可直接复制的环境变量配置
+ */
+
+import crypto from 'crypto';
+
+console.log('🔐 微信服务号Token和EncodingAESKey生成器');
+console.log('='.repeat(60));
+console.log('');
+
+// ==================== 1. 生成Token ====================
+
+console.log('🔑 生成Token（用于签名验证）...\n');
+
+function generateToken(length: number = 32): string {
+  // 生成随机字符串（只包含字母和数字）
+  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+  let token = '';
+  const randomBytes = crypto.randomBytes(length);
+  
+  for (let i = 0; i < length; i++) {
+    token += chars[randomBytes[i] % chars.length];
+  }
+  
+  return token;
+}
+
+const token = generateToken(32);
+
+console.log('  生成的Token:');
+console.log(`  ${token}`);
+console.log(`  长度: ${token.length}位`);
+console.log(`  说明: 用于URL验证和消息签名验证`);
+console.log('');
+
+// ==================== 2. 生成EncodingAESKey ====================
+
+console.log('🔐 生成EncodingAESKey（用于消息加解密）...\n');
+
+function generateEncodingAESKey(): string {
+  // 生成43位随机字符串（Base64字符集，不包含/+=）
+  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+  let aesKey = '';
+  const randomBytes = crypto.randomBytes(43);
+  
+  for (let i = 0; i < 43; i++) {
+    aesKey += chars[randomBytes[i] % chars.length];
+  }
+  
+  return aesKey;
+}
+
+const aesKey = generateEncodingAESKey();
+
+console.log('  生成的EncodingAESKey:');
+console.log(`  ${aesKey}`);
+console.log(`  长度: ${aesKey.length}位`);
+console.log(`  说明: 用于消息加密和解密（安全模式必需）`);
+console.log('');
+
+// ==================== 3. 输出环境变量配置 ====================
+
+console.log('='.repeat(60));
+console.log('\n📋 环境变量配置（复制以下内容到 backend/.env 文件）\n');
+console.log('='.repeat(60));
+console.log('');
+
+console.log('# ==========================================');
+console.log('# 微信服务号配置（患者端）');
+console.log('# ==========================================');
+console.log('');
+console.log('# 微信服务号基础配置');
+console.log('WECHAT_MP_APP_ID=wx062568ff49e4570c');
+console.log('WECHAT_MP_APP_SECRET=c0d19435d1a1e948939c16d767ec0faf');
+console.log('');
+console.log('# 微信服务号回调配置（消息加解密，安全模式）');
+console.log(`WECHAT_MP_TOKEN=${token}`);
+console.log(`WECHAT_MP_ENCODING_AES_KEY=${aesKey}`);
+console.log('');
+console.log('# 微信小程序配置（可选，后续开发）');
+console.log('WECHAT_MINI_APP_ID=');
+console.log('');
+
+// ==================== 4. 输出微信公众平台配置 ====================
+
+console.log('='.repeat(60));
+console.log('\n📋 微信公众平台配置（复制以下内容到公众平台）\n');
+console.log('='.repeat(60));
+console.log('');
+
+console.log('登录地址：https://mp.weixin.qq.com/');
+console.log('配置路径：设置与开发 → 基本配置 → 服务器配置');
+console.log('');
+console.log('配置参数：');
+console.log('');
+console.log('  【URL】');
+console.log('  生产环境：https://iit.xunzhengyixue.com/api/v1/iit/patient-wechat/callback');
+console.log('  开发环境：https://devlocal.xunzhengyixue.com/api/v1/iit/patient-wechat/callback');
+console.log('');
+console.log('  【Token】');
+console.log(`  ${token}`);
+console.log('');
+console.log('  【EncodingAESKey】');
+console.log(`  ${aesKey}`);
+console.log('');
+console.log('  【消息加解密方式】');
+console.log('  安全模式（推荐）');
+console.log('');
+console.log('  【数据格式】');
+console.log('  XML');
+console.log('');
+
+// ==================== 5. 输出后续步骤 ====================
+
+console.log('='.repeat(60));
+console.log('\n📝 后续步骤\n');
+console.log('='.repeat(60));
+console.log('');
+
+console.log('Step 1: 更新环境变量');
+console.log('  1. 复制上面的环境变量配置');
+console.log('  2. 粘贴到 backend/.env 文件');
+console.log('  3. 保存文件');
+console.log('');
+
+console.log('Step 2: 验证配置');
+console.log('  运行配置检查脚本：');
+console.log('  npx tsx src/modules/iit-manager/test-patient-wechat-config.ts');
+console.log('');
+
+console.log('Step 3: 启动服务');
+console.log('  本地开发：npm run dev');
+console.log('  生产环境：部署到SAE');
+console.log('');
+
+console.log('Step 4: 配置微信公众平台');
+console.log('  1. 登录微信公众平台');
+console.log('  2. 填写上面的配置参数');
+console.log('  3. 点击"提交"进行URL验证');
+console.log('  4. 验证成功后点击"启用"');
+console.log('');
+
+console.log('Step 5: 测试功能');
+console.log('  运行URL验证测试脚本：');
+console.log('  npx tsx src/modules/iit-manager/test-patient-wechat-url-verify.ts');
+console.log('');
+
+console.log('='.repeat(60));
+console.log('\n⚠️  重要提示\n');
+console.log('='.repeat(60));
+console.log('');
+
+console.log('  1. Token和EncodingAESKey必须在.env和微信公众平台中保持一致');
+console.log('  2. 不要将Token和EncodingAESKey提交到Git仓库');
+console.log('  3. 生产环境需要在SAE中配置这些环境变量');
+console.log('  4. 如果配置错误，可以重新运行本脚本生成新的值');
+console.log('  5. 修改配置后需要重启服务才能生效');
+console.log('');
+
+console.log('🎉 生成完成！');
+console.log('');
+