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/RegionController.cs

@@ -37,4 +37,46 @@ public class RegionController(RegionService service) : ControllerBase
         var deleted = await service.DeleteAsync(id, ct);
         return deleted ? NoContent() : NotFound();
     }
+
+    [HttpPut("{id:guid}/targets/{period}")]
+    public async Task<IActionResult> SetTarget(Guid id, string period, SetRegionalTargetRequest request, CancellationToken ct)
+    {
+        var result = await service.SetTargetAsync(id, period, request, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpPut("{id:guid}/budgets/{period}")]
+    public async Task<IActionResult> SetBudget(Guid id, string period, SetRegionalBudgetRequest request, CancellationToken ct)
+    {
+        var result = await service.SetBudgetAsync(id, period, request, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpPost("{id:guid}/agencies")]
+    public async Task<IActionResult> MapAgency(Guid id, MapAgencyToRegionRequest request, CancellationToken ct)
+    {
+        var result = await service.MapAgencyAsync(id, request, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpPut("{id:guid}/tax-rule")]
+    public async Task<IActionResult> SetTaxRule(Guid id, SetRegionalTaxRuleRequest request, CancellationToken ct)
+    {
+        var result = await service.SetTaxRuleAsync(id, request, ct);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpGet("{id:guid}/hierarchy")]
+    public async Task<IActionResult> GetHierarchy(Guid id)
+    {
+        var result = await service.GetHierarchyAsync(id);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpGet("{id:guid}/dashboard")]
+    public async Task<IActionResult> GetDashboard(Guid id, [FromQuery] string period)
+    {
+        var result = await service.GetDashboardAsync(id, period);
+        return result is null ? NotFound() : Ok(result);
+    }
 }