feat(plugin): add inspect-robots-wandb plugin for streaming metrics to Weights & Biases

[ujjwalredd]

Summary

Adds plugins/inspect-robots-wandb implementing WandbSink to stream evaluation runs, trial metrics, step counts, duration, and success rates to Weights & Biases dashboards.

Changes

• Created plugins/inspect-robots-wandb/ package with pyproject.toml, README.md, and WandbSink implementation.
• Registered entry point wandb = "inspect_robots_wandb.sink:wandb_sink" under inspect_robots.sinks.
• Added unit tests in plugins/inspect-robots-wandb/tests/test_wandb_sink.py achieving 100% test coverage.
• Updated .github/workflows/ci.yml with plugin-wandb job and ci-ok dependency.
• Updated CHANGELOG.md.

Checklist

• pre-commit install done; hooks pass
• Tests added/updated
• Coverage stays at 100% (pytest --cov)
• ruff check . and ruff format --check . pass
• mypy passes (strict)
• CHANGELOG.md updated under "Unreleased"
• Public API changes are reflected in inspect_robots.__all__ and the API-snapshot test
• Core stays NumPy-only (new deps are optional extras, lazily imported)

Related

Closes #365