Fix Product filtering and add kit disassembly functionality

Fixed:
- Replace is_active with status='active' for Product filtering in IncomingModelForm
- Product model uses status field instead of is_active

Added:
- Showcase field to ProductKit for tracking showcase placement
- product_kit field to Reservation for tracking kit-specific reservations
- Disassemble button in POS terminal for showcase kits
- API endpoint for kit disassembly (release reservations, mark discontinued)
- Improved reservation filtering when dismantling specific kits

Changes:
- ShowcaseManager now links reservations to specific kit instances
- POS terminal modal shows disassemble button in edit mode
- Kit disassembly properly updates stock aggregates

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

myproject/inventory/services/showcase_manager.py

@@ -67,6 +67,7 @@ class ShowcaseManager:
                             product=kit_item.product,
                             warehouse=warehouse,
                             showcase=showcase,
+                            product_kit=product_kit,
                             quantity=component_quantity,
                             status='reserved'
                         )
@@ -84,6 +85,7 @@ class ShowcaseManager:
                                 product=first_variant.product,
                                 warehouse=warehouse,
                                 showcase=showcase,
+                                product_kit=product_kit,
                                 quantity=component_quantity,
                                 status='reserved'
                             )
@@ -250,10 +252,8 @@ class ShowcaseManager:
                 )
 
                 if product_kit:
-                    # Если указан конкретный комплект, фильтруем резервы
-                    # TODO: добавить связь резерва с конкретным экземпляром комплекта
-                    # Пока освобождаем все резервы витрины
-                    pass
+                    # Если указан конкретный комплект, фильтруем только его резервы
+                    reservations = reservations.filter(product_kit=product_kit)
 
                 released_count = reservations.count()
 
@@ -264,6 +264,11 @@ class ShowcaseManager:
                         'message': f'На витрине "{showcase.name}" нет активных резервов'
                     }
 
+                # Сохраняем список затронутых товаров и склад ДО обновления резервов
+                from inventory.models import Stock
+                affected_products = list(reservations.values_list('product_id', flat=True).distinct())
+                warehouse = showcase.warehouse
+
                 # Освобождаем резервы
                 reservations.update(
                     status='released',
@@ -272,13 +277,11 @@ class ShowcaseManager:
                 )
 
                 # Обновляем агрегаты Stock
-                from inventory.models import Stock
-                affected_products = reservations.values_list('product_id', flat=True).distinct()
                 for product_id in affected_products:
                     try:
                         stock = Stock.objects.get(
                             product_id=product_id,
-                            warehouse=showcase.warehouse
+                            warehouse=warehouse
                         )
                         stock.refresh_from_batches()
                     except Stock.DoesNotExist: