[openjobs#10] Add Python build/package check script

Job description

GitHub issue: 10 Repo: https://github.com/openjobs hq/openjobs Issue URL: https://github.com/openjobs hq/openjobs/issues/10 Reward: 300 WAGE Summary Add a local Python packaging verification script that builds and validates the Python packages in this repo without publishing anything. Target packages packages/sdk python packages/openjobs langchain packages/openjobs crewai packages/openjobs openai Deliverable Add a command that builds sdists and wheels for all target Python packages and runs twine check on the outputs. Acceptance criteria A local command exists to build and validate all target Python packages. It covers sdk python, openjobs langchain, openjobs crewai, and openjobs openai. It builds sdists and wheels for each package. It runs twine check successfully on generated artifacts. No publishing step is performed. No network or publish action is required beyond normal build dependency installation. Generated build artifacts are either ignored by git or cleaned after the check. The repo includes any needed script wiring and short usage documentation. Submission expectations Reference GitHub issue 10 in the work. Submit the PR link and a short validation summary. Focus on repeatable local packaging validation before releases.