feat: 后端架构重构 — Endpoint→Service→Repository分层 + AI确认机制 + 异步任务持久化

- 核心业务拆分为 Endpoint → Application Service → Repository 三层
- AI写入操作必须用户确认后才写库(确认卡片机制)
- 报告/饮食/用药分析改为持久化任务队列(原子领取/重试/重启恢复)
- 运动计划修复: 连续真实日期替代周模板
- 用药提醒去重 + 通知Outbox预留
- 认证收拢到AuthService, 管理员收拢到AdminService
- AI会话加用户归属校验防串号
- 提示词调整为患者视角
- 开发假数据已关闭
- 21/21测试通过, 0警告0错误

backend/src/Health.Infrastructure/Notifications/EfInAppNotificationRepository.cs

@@ -0,0 +1,26 @@
+using Health.Application.Notifications;
+
+namespace Health.Infrastructure.Notifications;
+
+public sealed class EfInAppNotificationRepository(AppDbContext db) : IInAppNotificationRepository
+{
+    private readonly AppDbContext _db = db;
+
+    public async Task<IReadOnlyList<InAppNotificationRecord>> GetPendingAsync(Guid userId, CancellationToken ct) =>
+        await _db.NotificationOutbox.AsNoTracking()
+            .Where(x => x.UserId == userId && x.Status == "AwaitingProvider")
+            .OrderBy(x => x.CreatedAt)
+            .Take(10)
+            .Select(x => new InAppNotificationRecord(x.Id, x.Type, x.Payload, x.CreatedAt))
+            .ToListAsync(ct);
+
+    public async Task<bool> AcknowledgeAsync(Guid userId, Guid notificationId, CancellationToken ct)
+    {
+        var updated = await _db.NotificationOutbox
+            .Where(x => x.Id == notificationId && x.UserId == userId && x.Status == "AwaitingProvider")
+            .ExecuteUpdateAsync(setters => setters
+                .SetProperty(x => x.Status, "InAppDelivered")
+                .SetProperty(x => x.UpdatedAt, DateTime.UtcNow), ct);
+        return updated > 0;
+    }
+}