[jamiesun]

Summary

• bump the scorekit package version from 0.3.0 to 0.3.1
• keep Cargo.toml and Cargo.lock aligned for the tag release gate
• release the build validation, suite rollback, schema, and reproducibility fixes merged in PR fix: harden build validation and rollback #12

Validation

• cargo fmt --check
• cargo clippy --all-targets --locked -- -D warnings
• cargo test --locked: 101 passed
• cargo build --release --locked
• release binary reports scorekit 0.3.1