持久层重构为独立 MiGu.DB 工程并优化集成

- 新增 MiGu.DB 项目，迁移所有领域实体与枚举，统一模型约定
- 实现 Entity/Repository/UoW/Provider/Exception 等接口与实现
- 支持数据修补机制，完善 Sqlite 初始迁移与数据库管理
- Server 侧移除 EF Core 相关，依赖 MiGu.DB，PlatformPersistence 适配
- 业务服务注入 UoW/Repository，状态字段统一用 enum 及辅助类
- 统一异常处理，Controller 映射 HTTP 状态码
- 配置项与文档补充数据库启动、SchemaMode、迁移说明
- 新增 GlobalUsings.Db.cs、WmsStatusAliases.cs 简化类型引用
- 新增 HttpActorContextMiddleware 支持操作者上下文一致性
- 新增 MiGuDbContextModelSnapshot 追踪数据库结构
- 优化代码结构，解耦领域与持久层，提升扩展性与安全性

MiGu.Server/MiGu.Server.csproj

@@ -16,11 +16,14 @@
     <PackageReference Include="Yarp.ReverseProxy" Version="2.2.0" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.10" />
     <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="8.0.2" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.10" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="8.0.10" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="8.0.10" />
-    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="8.0.10" />
-    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="8.0.2" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.10">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\MiGu.DB\MiGu.DB.csproj" />
   </ItemGroup>
 
   <ItemGroup>