fix: use local nuget cache for faster docker build

src/Api/TakeoutSaaS.AdminApi/Dockerfile

@@ -1,6 +1,9 @@
 FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
 WORKDIR /src
 
+# 复制预先准备好的 NuGet 包缓存
+COPY --from=nuget-cache / /root/.nuget/packages/
+
 # Copy only what's needed for restore first, so `dotnet restore` can be cached.
 COPY ["Directory.Build.props", "./"]
 COPY ["TakeoutSaaS.sln", "./"]