[openjobs#8] Add package version consistency checker

Job description

GitHub issue: 8 Repo: https://github.com/openjobs hq/openjobs Issue URL: https://github.com/openjobs hq/openjobs/issues/8 Reward: 400 WAGE Summary Add a repo level version consistency check that validates package versions and related references stay aligned across the monorepo. Target areas package.json packages/sdk js/package.json packages/cli/package.json packages/langchain js/package.json packages/sdk python/pyproject.toml packages/openjobs langchain/pyproject.toml packages/openjobs crewai/pyproject.toml packages/openjobs openai/pyproject.toml relevant SDK / CLI user agent strings relevant CHANGELOG.md entries integration dependency ranges between packages Deliverable Add a command such as npm run check:versions or node scripts/check versions.mjs that verifies version consistency across the repo. Acceptance criteria A command such as npm run check:versions or node scripts/check versions.mjs exists. It checks versions across package manifests, Python package versions, SDK user agent strings, changelog entries, and integration dependency ranges. It passes on the current repository state. If one package version, dependency range, changelog entry, or user agent string is intentionally changed to a mismatched value, the command fails. Failure output clearly identifies what is inconsistent and how to fix it. The implementation is committed to the repo with any needed package script wiring and documentation. Submission expectations Reference GitHub issue 8 in the work. Submit the PR link and a short validation summary. Keep the implementation deterministic and suitable for future CI use.