Refactor sales pipeline: ShopPO, Invoice, SysConfig models

Major refactor replacing Sale/Order with ShopPO → Invoice → LoadingSheet flow. Removed legacy Sale/Order models and features; introduced ShopPO, ShopPOItem, Invoice, LoadingSheetOrder, and SysConfig models. Updated related entities, enums, repositories, and controllers. Added new migrations for schema changes and system config. Overhauled business logic and DI registrations. Updated documentation with migration plan.

Distribution/Features/Region/IRegionRepository.cs

@@ -42,5 +42,5 @@ public interface IRegionRepository
     Task<List<Models.Route>> GetRoutesAsync(Guid regionId);
     Task<List<Models.Store>> GetStoresByRouteIdsAsync(List<Guid> routeIds);
 
-    Task<List<Models.Order>> GetOrdersForDashboardAsync(Guid regionId, DateTime periodStart, DateTime periodEndExclusive);
+    Task<List<Models.ShopPO>> GetOrdersForDashboardAsync(Guid regionId, DateTime periodStart, DateTime periodEndExclusive);
 }

Distribution/Features/Region/RegionRepository.cs

@@ -129,11 +129,11 @@ public class RegionRepository(AppDBContext context) : IRegionRepository
     public async Task<List<Models.Store>> GetStoresByRouteIdsAsync(List<Guid> routeIds) =>
         await context.Stores.Where(s => routeIds.Contains(s.FK_RouteId) && s.IsActive).ToListAsync();
 
-    public async Task<List<Models.Order>> GetOrdersForDashboardAsync(Guid regionId, DateTime periodStart, DateTime periodEndExclusive) =>
-        await (from o in context.Orders
+    public async Task<List<Models.ShopPO>> GetOrdersForDashboardAsync(Guid regionId, DateTime periodStart, DateTime periodEndExclusive) =>
+        await (from o in context.ShopPOs
                join s in context.Stores on o.FK_StoreId equals s.Id
                join r in context.Routes on s.FK_RouteId equals r.Id
                where r.FK_RegionId == regionId && o.IsActive && s.IsActive && r.IsActive
-                     && o.OrderDate >= periodStart && o.OrderDate < periodEndExclusive
+                     && o.CreatedAt >= periodStart && o.CreatedAt < periodEndExclusive
                select o).ToListAsync();
 }

Distribution/Features/Region/RegionService.cs

@@ -219,7 +219,7 @@ public class RegionService(IRegionRepository repo, IUnitOfWork uow, ICurrentUser
             budget?.BudgetAmount,
             orders.Count,
             orders.Sum(o => o.TotalAmount),
-            orders.Count == 0 ? null : orders.Max(o => o.OrderDate),
+            orders.Count == 0 ? null : orders.Max(o => o.CreatedAt),
             taxRule?.RuleConfig,
             agencyMaps.Select(m => m.FK_AgencyUserId).ToList());
     }