feat: integrate PYMS payment gateway, add blog/sitepage/image services, local file manager

Payment Gateway:
- Add PYMSPaymentService: IPaymentGatewayService via gRPC to PYMS microservice
- Add ZarinPalPaymentService: direct ZarinPal integration (backup)
- Register 'pyms' payment provider in DI ConfigureServices
- Add PYMS proto files (pyms_transaction.proto, pyms_public_messages.proto)
- Fix VerifyDiscountWalletCharge: pass 'OK' as status instead of Authority
- Update appsettings: PaymentProvider=pyms, sandbox mode, merchant ID

Blog System:
- Add BlogCategory, BlogPost, BlogPostImage entities and CQRS
- Add proto files and gRPC services for blog management
- Add Mapster profiles for blog responses

Content Management:
- Add SitePage entity and CQRS for static pages
- Add proto and gRPC service for site pages

Image/File Management:
- Add LocalFileManager with disk storage + base64 serving + FMS fallback
- Add ImagePathResolverInterceptor for gRPC responses
- Add ImageResolverService for explicit image resolution
- Add UploadsController for public file serving with FMS fallback
- Add PaymentCallbackController for discount order payment callbacks

Database:
- Add blog and content entity migrations
- Remove ImagePath MaxLength constraints
- Remove old FileManagementService (replaced by LocalFileManager)

src/CMSMicroservice.WebApi/Services/ProductsService.cs

@@ -178,6 +178,7 @@ public class ProductsService : ProductsContract.ProductsContractBase
             CategoryIds = request.Filter?.CategoryId.HasValue == true 
                 ? new List<long> { request.Filter.CategoryId.Value } 
                 : new List<long>(),
+            IsActive = request.Filter?.IsActive,
             SortBy = request.SortBy ?? string.Empty,
             PaginationState = request.PaginationState != null 
                 ? new AppModels.PaginationState 
@@ -216,7 +217,8 @@ public class ProductsService : ProductsContract.ProductsContractBase
                 SaleCount = m.SaleCount,
                 ViewCount = m.ViewCount,
                 RemainingCount = m.RemainingCount,
-                CategoryIds = { m.Categories?.Select(c => c.CategoryId) ?? Enumerable.Empty<long>() }
+                CategoryIds = { m.Categories?.Select(c => c.CategoryId) ?? Enumerable.Empty<long>() },
+                IsActive = m.IsActive
             }) }
         };
     }