What is the renamed class for BaseVolk in the target codebase?

The BaseVolk class from the source orchestrata monorepo is renamed to BaseAgent in orchestrata-ultimate. This is part of the broader rename where all *Volk classes become *Agent classes (e.g., AnalystVolk → AnalystAgent, SeniorDevVolk → SeniorDevAgent). The mapping is defined in plans/class-mapping.json.