chore: 全面规范化代码，遵循 CLAUDE.md 编码规范

- C# 文件命名改为 snake_case（28 个文件重命名）
- C# 类转换为主构造函数（8 个类）
- 空 catch 添加异常类型（2 处）
- 新建 GlobalUsings.cs（Health.Infrastructure、Health.WebApi）
- Flutter 移除 go_router，改用 Riverpod 路由栈
- Flutter 移除 flutter_secure_storage，改用 sqflite 持久化
- 修复 Flutter 构建路径（Flutter SDK 迁至 D 盘）
- 后端端口改为 0.0.0.0:5000，支持局域网访问

backend/src/Health.Domain/Entities/report.cs

@@ -0,0 +1,26 @@
+using Health.Domain.Enums;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Health.Domain.Entities;
+
+/// <summary>
+/// 检查报告
+/// </summary>
+public sealed class Report
+{
+    public Guid Id { get; set; }
+    public Guid UserId { get; set; }
+    public string FileUrl { get; set; } = string.Empty;
+    public ReportFileType FileType { get; set; }
+    public ReportCategory Category { get; set; }
+    public string? AiSummary { get; set; }        // AI 预解读结果
+    [Column(TypeName = "jsonb")]
+    public string? AiIndicators { get; set; }      // JSONB: [{name, value, unit, range, status}]
+    public ReportStatus Status { get; set; }
+    public string? DoctorComment { get; set; }     // 医生审核意见
+    public string? DoctorName { get; set; }
+    public DateTime? ReviewedAt { get; set; }
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+    public User User { get; set; } = null!;
+}