feat(mp): App 级告警长轮询 + 健康总览 TS 修复

- 新增 useAlertPolling hook：10s 间隔轮询 critical 告警
- requestUnlimited 独立通道，不占并发槽位
- generation counter 防重叠 + 失败指数退避(max 30s/10次)
- 新告警弹窗 Taro.showModal + TabBar 角标
- 修复 HealthThreshold 属性名(indicator/level 非 indicator_name/severity)
- 修复 usePageData fetchData 返回类型

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

@@ -64,15 +64,15 @@ export default function Health() {
     if (!thresholds.length) return null;
     const th = thresholds;
     if (type === 'blood_pressure') {
-      const v = th.find((t) => t.indicator_name === 'systolic_bp' && t.severity === 'high');
+      const v = th.find((t) => t.indicator === 'systolic_bp' && t.level === 'high');
       return v?.threshold_value ?? 140;
     }
     if (type === 'heart_rate') {
-      const v = th.find((t) => t.indicator_name === 'heart_rate' && t.severity === 'high');
+      const v = th.find((t) => t.indicator === 'heart_rate' && t.level === 'high');
       return v?.threshold_value ?? 100;
     }
     if (type === 'blood_sugar') {
-      const v = th.find((t) => t.indicator_name === 'blood_sugar_fasting' && t.severity === 'high');
+      const v = th.find((t) => t.indicator === 'blood_sugar_fasting' && t.level === 'high');
       return v?.threshold_value ?? 6.1;
     }
     return null;