Adds RegionalTargetResponse, RegionalBudgetResponse,
RegionAgencyMapResponse, RegionalTaxRuleResponse,
RegionHierarchyResponse, and RegionDashboardResponse types, plus
setTarget/setBudget/mapAgency/setTaxRule/hierarchy/dashboard methods
on the regions API client, mirroring the new backend endpoints.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>