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.Application/Diets/DietContracts.cs

@@ -0,0 +1,51 @@
+using Health.Domain.Entities;
+using Health.Domain.Enums;
+
+namespace Health.Application.Diets;
+
+public sealed record DietFoodItemInput(
+    string Name,
+    string? Portion,
+    int? Calories,
+    int SortOrder);
+
+public sealed record DietRecordCreateRequest(
+    MealType MealType,
+    int? TotalCalories,
+    int? HealthScore,
+    DateOnly RecordedAt,
+    IReadOnlyList<DietFoodItemInput> FoodItems);
+
+public sealed record DietRecordPatchRequest(
+    int? TotalCalories,
+    int? HealthScore);
+
+public sealed record DietFoodItemDto(
+    string Name,
+    string? Portion,
+    int? Calories);
+
+public sealed record DietRecordDto(
+    Guid Id,
+    string MealType,
+    int? TotalCalories,
+    int? HealthScore,
+    DateOnly RecordedAt,
+    IReadOnlyList<DietFoodItemDto> FoodItems);
+
+public interface IDietService
+{
+    Task<IReadOnlyList<DietRecordDto>> ListAsync(Guid userId, string? date, string? mealType, CancellationToken ct);
+    Task<Guid> CreateAsync(Guid userId, DietRecordCreateRequest request, CancellationToken ct);
+    Task<bool> DeleteAsync(Guid userId, Guid recordId, CancellationToken ct);
+    Task<bool> UpdateAsync(Guid userId, Guid recordId, DietRecordPatchRequest request, CancellationToken ct);
+}
+
+public interface IDietRepository
+{
+    Task<IReadOnlyList<DietRecord>> ListAsync(Guid userId, DateOnly? recordedAt, MealType? mealType, CancellationToken ct);
+    Task<DietRecord?> GetOwnedAsync(Guid userId, Guid recordId, CancellationToken ct);
+    Task AddAsync(DietRecord record, CancellationToken ct);
+    void Delete(DietRecord record);
+    Task SaveChangesAsync(CancellationToken ct);
+}