Add version-bump CI guard for Cargo and pyproject

Type

Task

Scope

Multi-theme or Platform

Skillset

engineering

Description

Context

Once #144 lands, the Python wheel and the Rust crate have independent version numbers. Nothing catches a missing bump today until publish time — a PR can merge, then fail to release.

Proposed change

Add a version-bump-guard job to .github/workflows/ci.yaml:

• Diff the PR against main. If any Python-facing file changed (src/python.rs, python/**, pyproject.toml), require pyproject.toml's version to differ from main's.
• Same rule for Rust: if any other file under src/ or Cargo.toml changed, require Cargo.toml's [package].version to differ.
• Fail with a message naming which file to bump.