feat(miniprogram): 关怀模式 Phase 2 — Design Token + 15 页面批量接入

- 新建 useElderClass hook，替代每页 3 行样板代码
- 新建 CSS 自定义属性 Design Token 系统（tokens.scss）
  正常/关怀两套值：字号、间距、触控、布局参数
- 15 个页面批量接入关怀模式 class：
  TabBar: 商城页
  主流程: 预约列表/详情/创建、咨询详情
  子包: 体征录入/趋势/日常监测/告警、用药/档案/随访/报告/家庭/设置
- 新建 elder-toast 工具（关怀模式 3s + 触觉反馈）
- 页面覆盖率：4/59 → 22/59 (37%)

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

apps/miniprogram/src/pages/health/index.tsx

@@ -3,7 +3,7 @@ import { View, Text, Input } from '@tarojs/components';
 import Taro, { useDidShow, usePullDownRefresh } from '@tarojs/taro';
 import { useHealthStore } from '../../stores/health';
 import { useAuthStore } from '../../stores/auth';
-import { useUIStore } from '../../stores/ui';
+import { useElderClass } from '../../hooks/useElderClass';
 import { inputVitalSign, getTrend, getHealthThresholds, findThreshold, DEFAULT_THRESHOLDS, type HealthThreshold } from '../../services/health';
 import { listPendingSuggestions, type AiSuggestionItem } from '../../services/ai-analysis';
 import Loading from '../../components/Loading';
@@ -43,8 +43,7 @@ interface TrendPoint {
 export default function Health() {
   const { todaySummary, loading, refreshToday, getTrend: fetchTrend } = useHealthStore();
   const { user, currentPatient } = useAuthStore();
-  const { mode } = useUIStore();
-  const modeClass = mode === 'elder' ? 'elder-mode' : '';
+  const modeClass = useElderClass();
   const [activeTab, setActiveTab] = useState<VitalType>('blood_pressure');
   const [systolic, setSystolic] = useState('');
   const [diastolic, setDiastolic] = useState('');