fix(mp): 行业标准第二轮审计修复 — 安全存储+UX+合规

- 安全：AI聊天历史、患者档案、设备同步数据统一走 secureSet/secureGet 加密存储
- 合规：TabBar "消息" 改为 "助手" 消除命名误导
- 合规：新增 .env.production 模板配置 HTTPS API URL
- UX：AI发送按钮 40→44px、反馈按钮 32→44px、协议勾选框 44px 点击热区
- UX：5处硬编码 10-12px 字号替换为 design token（DoctorTabBar/ShortcutButton/TodoAlert/mall）
- UX：6处安全区域写法统一（全部使用 --tk-page-padding/--tk-tabbar-space + env fallback）
- 新增 safe-bottom-padded / safe-bottom-tabbar 两个 mixin

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/miniprogram/src/app.config.ts

@@ -74,7 +74,7 @@ export default defineAppConfig({
     list: [
       { pagePath: 'pages/index/index', text: '首页', iconPath: 'assets/tabbar/home.png', selectedIconPath: 'assets/tabbar/home-active.png' },
       { pagePath: 'pages/health/index', text: '健康', iconPath: 'assets/tabbar/health.png', selectedIconPath: 'assets/tabbar/health-active.png' },
-      { pagePath: 'pages/messages/index', text: '消息', iconPath: 'assets/tabbar/message.png', selectedIconPath: 'assets/tabbar/message-active.png' },
+      { pagePath: 'pages/messages/index', text: '助手', iconPath: 'assets/tabbar/message.png', selectedIconPath: 'assets/tabbar/message-active.png' },
       { pagePath: 'pages/profile/index', text: '我的', iconPath: 'assets/tabbar/profile.png', selectedIconPath: 'assets/tabbar/profile-active.png' },
     ],
   },