build: 更新 .npmrc，添加 CXXFLAGS 和 CL 的导出配置

Author: cute-omega

.npmrc

@@ -3,4 +3,6 @@ shamefully-hoist=true
 # In CI, CXXFLAGS=-std=c++17 (Linux/macOS) and CL=/std:c++17 (Windows) are
 # set before `pnpm install` so node-gyp compiles with the correct standard.
 # For local builds on Linux/macOS you may need:
-#   export CXXFLAGS="-std=c++17"
+export CXXFLAGS="-std=c++17"
+# For local builds on Windows you may need:
+export CL="/std:c++17"