Add CybORG arena

[Muhtasham]

Summary

• add a CybORG arena backed by the CAGE Challenge 3 DroneSwarm simulation
• add a Docker/runtime adapter that installs pinned CybORG v3.0 from source with the NumPy compatibility pin
• register the arena, add a dummy smoke config, docs, README mention, and unit coverage for validation/results/execution
• keep the adapter simulation-only: no live exploit tooling, external network targets, or real cyber operations
• rebase cleanly on top of merged SCML PR Add SCML arena #100 and resolve the shared README arena-section conflict

Verification

Post-SCML rebase verification run locally:

• uv run ruff check codeclash/arenas/cyborg tests/arenas/test_cyborg.py codeclash/arenas/__init__.py
• uv run pytest tests/arenas/test_cyborg.py
• uv run --with 'numpy<1.24' --with-editable /tmp/CybORG-codeclash python codeclash/arenas/cyborg/runtime/run_cyborg.py --agent alpha=codeclash/arenas/cyborg/runtime/cyborg_agent.py --agent beta=codeclash/arenas/cyborg/runtime/cyborg_agent.py --episodes 2 --steps 5 --drones 8 --output /tmp/cyborg-direct-post-scml.json\n- uv run python main.py configs/examples/CybORG__dummy__r1__s2.yaml -o /tmp/codeclash-cyborg-post-scml-smoke\n- uv run pytest -v --cov --cov-branch --cov-report=xml -n auto (185 passed)\n- uv run mkdocs build\n- npx --yes markdown-link-check -c .github/mlc_config.json $(git ls-files '*.md')\n- git diff --check\n\nEarlier pre-rebase validation also included a cold Docker image rebuild for codeclash/cyborg after docker rmi codeclash/cyborg.\n\n## Notes\n- CybORG upstream v3.0 is installed editable from a checked-out repository because the packaged install path is missing CybORG/version.txt.\n- numpy<1.24 is required because CybORG v3.0 still uses deprecated NumPy aliases such as np.int.\n- Repo-wide ruff check . still has unrelated pre-existing BattleCode/Chess lint drift; that should be handled in a separate cleanup PR.