ci: add GitHub Actions workflow for OABP conformance tests (Fixes #38)

[unsiqasik]

Summary

Adds a GitHub Actions workflow to run the OABP conformance test suite on every push and PR to main.

Changes

• New file: .github/workflows/conformance.yml
  • Triggers on push and pull_request to main
  • Sets up Python 3.12
  • Installs pytest
  • Runs cd sdk/python && python -m pytest tests/ -v
• Updated: README.md
  • Added CI status badge at the top

Testing

• The workflow will run on this PR itself, verifying it works
• Conformance tests at sdk/python/tests/test_oabp_conformance.py use stdlib only, so no additional install step needed beyond pytest

Related Issues

Fixes #38

[Aigen-Protocol]

Thanks — workflow file is clean and the test path sdk/python/tests/ exists in main. Status: merge is blocked on our side because the GitHub App auth the operator uses to merge lacks workflow scope. The operator needs to run gh auth refresh -s workflow from their terminal before this can land. Tracked in our internal queue; will merge as soon as that's done — nothing more required from you. Workflow will then run on subsequent PRs.