Add region target/budget/tax-rule/agency-map/hierarchy/dashboard APIs

Extends RegionService, RegionRepository, and RegionController with the
endpoints from mainPlan.md sec 2 beyond plain CRUD: setRegionalTarget,
setRegionalBudget, mapAgencyToRegion, setRegionalTaxRule,
getRegionHierarchy, and getRegionDashboard. Target/budget/tax-rule
mutation is gated to users with region scope at RegionalManager level
or RegionalAgency level across all regions; mapAgencyToRegion links an
existing User holding the RegionalAgency role rather than introducing
a separate agency entity, matching the convention already used by
Claim.FK_AgencyUserId elsewhere in the codebase.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Distribution/Features/Region/RegionDTOs.cs

@@ -5,3 +5,32 @@ public record CreateRegionRequest(string Name);
 public record UpdateRegionRequest(string Name);
 
 public record RegionResponse(Guid Id, string Name, bool IsActive, DateTime CreatedAt);
+
+public record SetRegionalTargetRequest(decimal TargetValue);
+
+public record SetRegionalBudgetRequest(decimal BudgetAmount);
+
+public record MapAgencyToRegionRequest(Guid AgencyUserId);
+
+public record SetRegionalTaxRuleRequest(string RuleConfig);
+
+public record RegionalTargetResponse(Guid RegionId, string Period, decimal TargetValue);
+
+public record RegionalBudgetResponse(Guid RegionId, string Period, decimal BudgetAmount);
+
+public record RegionAgencyMapResponse(Guid RegionId, Guid AgencyUserId);
+
+public record RegionalTaxRuleResponse(Guid RegionId, string RuleConfig);
+
+public record RegionHierarchyRouteItem(Guid RouteId, string RouteName, List<Guid> StoreIds);
+
+public record RegionHierarchyResponse(Guid RegionId, string RegionName, List<RegionHierarchyRouteItem> Routes);
+
+public record RegionDashboardResponse(
+    Guid RegionId,
+    string Period,
+    decimal? TargetValue,
+    decimal? BudgetAmount,
+    int OrderCount,
+    decimal ActualSales,
+    DateTime? LastOrderDate);