FieldYield and FieldKindData.Yields (key 3), ProvinceData, FieldKinds.Pick/Assign/Ensure/Yield
with a province type, Provinces.Regions/Partition/Deal, Galaxy.Provinces built once by the
generation and save constructors, SavedGame key 15 and SavedZone key 6, ProvinceZones setting.
Not yet built or run; tests follow in the next commit.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>