chore(ci): add requirements.txt and pre-commit hook for Snyk support

[fyzanshaik-atlan]

Summary

This PR adds requirements.txt and a pre-commit hook to support Snyk GitHub App integration.

Changes

• Added modelcontextprotocol/requirements.txt

  • Auto-generated from uv.lock using uv export
  • Required for Snyk GitHub App to detect Python dependencies

• Updated .pre-commit-config.yaml

  • Added local hook to automatically sync requirements.txt when uv.lock or pyproject.toml changes
  • Ensures requirements.txt stays in sync with uv.lock

Notes

• requirements.txt should not be manually edited
• Run uv export --all-extras --no-hashes > requirements.txt to update
• The pre-commit hook will block commits if requirements.txt is out of sync