Adds the npc-staffing and labor-classifications collections, a shared staffing field factory applied to both structure blueprints (Staffing Defaults group) and game structure instances, blueprint-derived staffing defaults on game structure create, staff-hiring toggles on Game Rules, and their database migrations.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
