Profiling irohadatamodel Build

To locate slow build steps in iroha_data_model, run the helper script:

./scripts/profile_build.sh

This runs cargo build -p iroha_data_model --timings and writes timing reports to target/cargo-timings/. Open cargo-timing.html in a browser and sort tasks by duration to see which crates or build steps take the most time.

Use the timings to focus optimization efforts on the slowest tasks.