feat(backend): report node platform, geo and build info

Agents and probes report OS, arch and build (version, tag, commit, time).
The backend looks up country and ISP of public addresses only, stores them
in node_meta (schema v5) and exposes display info via /api/public/nodes,
/api/public/about and /api/admin/build-info behind site.show_build.

scripts/publish.sh

@@ -16,17 +16,23 @@ case "$project" in
   *) echo "unknown project: $project" >&2; exit 2 ;;
 esac
 
+# 构建信息（程序里显示的 tag、提交、构建时间）：没在 git 仓库里就留空
+export MONITOR_TAG="${MONITOR_TAG:-$(git -C "$root" describe --tags --always --dirty 2>/dev/null || true)}"
+export MONITOR_COMMIT="${MONITOR_COMMIT:-$(git -C "$root" rev-parse --short=10 HEAD 2>/dev/null || true)}"
+export MONITOR_BUILT_AT="${MONITOR_BUILT_AT:-$(date -u +%Y-%m-%dT%H:%M:%SZ)}"
+build_env=(-e MONITOR_TAG -e MONITOR_COMMIT -e MONITOR_BUILT_AT)
+
 out="backend/artifacts/publish/$project/$rid"
 args=(publish "$csproj" -c Release -r "$rid" -p:PublishAot=true -p:DebugType=none -p:DebugSymbols=false -o "/src/$out" --artifacts-path /artifacts -nologo -v q)
 
 case "$rid" in
   linux-musl-x64)
     # SDK 镜像的版本可以比 global.json 新（rollForward = latestFeature）
-    docker run --rm -v "$root:/src" -v monitor-nuget:/root/.nuget -v "monitor-artifacts-$rid:/artifacts" -w /src \
+    docker run --rm "${build_env[@]}" -v "$root:/src" -v monitor-nuget:/root/.nuget -v "monitor-artifacts-$rid:/artifacts" -w /src \
       mcr.microsoft.com/dotnet/sdk:10.0-alpine-aot dotnet "${args[@]}"
     ;;
   linux-x64)
-    docker run --rm -v "$root:/src" -v monitor-nuget:/root/.nuget -v "monitor-artifacts-$rid:/artifacts" -w /src       mcr.microsoft.com/dotnet/sdk:10.0-noble-aot dotnet "${args[@]}"
+    docker run --rm "${build_env[@]}" -v "$root:/src" -v monitor-nuget:/root/.nuget -v "monitor-artifacts-$rid:/artifacts" -w /src       mcr.microsoft.com/dotnet/sdk:10.0-noble-aot dotnet "${args[@]}"
     ;;
   linux-musl-arm64|linux-arm64)
     echo "$rid needs an arm64 Alpine builder (native or qemu): run this script on an arm64 host or in CI" >&2