feat: 将数据库模型和迁移集中到 EFCore 项目

- 将 AppDataContext、实体模型、Migrations 从 Avalonia-Services 移动到 Avalonia-EFCore
- 更新 API、PC、Services 中的数据库上下文和实体引用命名空间
- 在实体上显式绑定表名、字段名和数据库注释
- 更新 InitialCreate、Designer、Snapshot，使用新的表名、字段名和注释
- 新增 AppDataContextFactory，支持 dotnet ef 设计时创建 DbContext
- 新增本地 dotnet-ef 工具清单
- 新增一键生成迁移脚本 add-migration.ps1 / .cmd / .bat
- 启动时自动检测并执行未应用迁移
- 从 appsettings.json 读取数据库配置

Avalonia-EFCore/Models/UserEntity.cs

@@ -0,0 +1,43 @@
+using Microsoft.EntityFrameworkCore;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Avalonia_EFCore.Models
+{
+    /// <summary>
+    /// 用户实体 —— 演示数据库 CRUD 操作。
+    /// </summary>
+    [Comment("用户实体，演示数据库 CRUD 操作")]
+    [Table("user")]
+    public class UserEntity
+    {
+        [Key]
+        [Comment("用户主键")]
+        [Column("id")]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        public int Id { get; set; }
+
+        [Comment("用户名称")]
+        [Column("name")]
+        [MaxLength(100)]
+        public string? Name { get; set; }
+
+        [Comment("用户邮箱")]
+        [Column("email")]
+        [MaxLength(200)]
+        public string? Email { get; set; }
+
+        [Comment("电话号码")]
+        [Column("phone-number")]
+        [MaxLength(50)]
+        public string? PhoneNumber { get; set; }
+
+        [Comment("创建时间")]
+        [Column("created-at")]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Comment("更新时间")]
+        [Column("updated-at")]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+    }
+}

Avalonia-EFCore/Models/WeatherForecast.cs

@@ -0,0 +1,13 @@
+namespace Avalonia_EFCore.Models
+{
+    public class WeatherForecast
+    {
+        public DateOnly Date { get; set; }
+
+        public int TemperatureC { get; set; }
+
+        public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
+
+        public string? Summary { get; set; }
+    }
+}

Avalonia-EFCore/Models/WeatherForecastEntity.cs

@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Avalonia_EFCore.Models
+{
+    /// <summary>
+    /// 天气预报数据实体。
+    /// </summary>
+    [Comment("天气预报数据实体")]
+    [Table("weather-forecast")]
+    public class WeatherForecastEntity
+    {
+        [Key]
+        [Comment("天气预报主键")]
+        [Column("id")]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        public int Id { get; set; }
+
+        [Comment("预报日期")]
+        [Column("date")]
+        public DateOnly Date { get; set; }
+
+        [Comment("摄氏温度")]
+        [Column("temperature-c")]
+        public int TemperatureC { get; set; }
+
+        [Comment("天气摘要")]
+        [Column("summary")]
+        [MaxLength(200)]
+        public string? Summary { get; set; }
+
+        [Comment("创建时间")]
+        [Column("created-at")]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Comment("更新时间")]
+        [Column("updated-at")]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+    }
+}