432d1d08d1
Add a small route-crate API that resolves a Windows network adapter GUID into its interface LUID and index. The TAP adapter discovery already gives us the NetCfgInstanceId GUID, and the route/metric work needs the corresponding IP interface identity before it can safely inspect or adjust TAP metrics. The implementation keeps GUID parsing local and dependency-free, then delegates the actual identity lookup to Windows IP Helper calls. Non-Windows builds expose the same API shape with a clear unsupported-platform error. Test Plan: - cargo fmt --check - cargo test --workspace - cargo clippy --workspace --all-targets -- -D warnings - cargo check -p lanparty-client-route --target x86_64-pc-windows-msvc - cargo clippy -p lanparty-client-route --target x86_64-pc-windows-msvc --all-targets -- -D warnings - git diff --check Refs: PLAN.md