chore(release): bump version to 0.1.4

[jesse-black]

Motivation

• Prepare a formal release by updating the crate version to 0.1.4 and keeping the package metadata consistent between manifest and lockfile.

Description

• Update version in Cargo.toml from 0.1.4-rc.0 to 0.1.4 and update the covgate package entry in Cargo.lock to match.

Testing

• Ran cargo xtask validate, which performs cargo fmt --check, cargo clippy, cargo llvm-cov and the full unit and integration test suite, and all checks passed.

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Codex Task