ci: share Linux restore artifacts before builds [CI]

packaging/container/Agent.Restore.Containerfile

@@ -0,0 +1,16 @@
+# Resolve a native Agent RID once in the shared Buildah store. Later build jobs
+# start from this image and reuse both project.assets.json and the NuGet cache.
+ARG NATIVEAOT_BUILDER_IMAGE=localhost/moshiro-dotnet10-nativeaot-aotanywhere:ci
+FROM --platform=linux/amd64 ${NATIVEAOT_BUILDER_IMAGE} AS toolchain
+FROM toolchain AS restore
+WORKDIR /src/backend
+COPY restore/backend/ ./
+ARG NODE_RID=linux-musl-arm64
+ARG STATIC_MSQUIC=true
+ENV NUGET_PACKAGES=/root/.nuget/packages
+RUN --mount=type=cache,id=moshiro-nuget,target=/root/.nuget/packages,sharing=locked \
+    --mount=type=bind,from=toolchain,source=/root/.nuget/packages,target=/opt/nuget-seed,ro \
+    cp -a --update=none /opt/nuget-seed/. /root/.nuget/packages/ \
+    && dotnet restore Agent.Native.proj -r "$NODE_RID" -p:PublishAot=true -p:UseAotAnywhere=true -p:SelfContained=true \
+       -p:StaticMsQuic="$STATIC_MSQUIC" -p:StaticExecutable="$STATIC_MSQUIC" \
+       -p:RuntimeFrameworkVersion=10.0.12 -p:InvariantGlobalization=true --artifacts-path /artifacts