ci: add Dockerfile for .NET 10 multi-stage build

Dockerfile

@@ -0,0 +1,21 @@
+# BuildFlow API (.NET 10) 多阶段构建
+FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
+WORKDIR /src
+
+# 先拷贝 sln 和 props,利用层缓存恢复 NuGet
+COPY BuildFlow.slnx Directory.Build.props ./
+COPY src/ ./src/
+
+# 还原 + 发布 Host (含全部模块)
+RUN dotnet publish src/BuildFlow.Host/BuildFlow.Host.csproj -c Release -o /app/publish /p:UseAppHost=false
+
+# 运行时镜像
+FROM mcr.microsoft.com/dotnet/aspnet:10.0
+WORKDIR /app
+COPY --from=build /app/publish ./
+
+# 容器内监听 5667 (与 appsettings 一致), 但绑定 0.0.0.0 以便外部访问
+ENV ASPNETCORE_URLS=http://0.0.0.0:5667
+EXPOSE 5667
+
+ENTRYPOINT ["dotnet", "BuildFlow.Host.dll"]