Add stock availability display to product list and detail views

- Add total_available, total_reserved, total_free annotations to product queries
- Display free stock (green/red) with reserved count in product list
- Show detailed stock info in product detail page (moved to top)
- Make reservation count clickable to view filtered reservations
- Add product filter support to ReservationListView
- Add product link in reservation list for easy navigation

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

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

myproject/products/views/product_views.py

@@ -5,7 +5,8 @@ from django.contrib import messages
 from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
 from django.views.generic import ListView, CreateView, DetailView, UpdateView, DeleteView
 from django.urls import reverse_lazy
-from django.db.models import Q
+from django.db.models import Q, Sum, Value, DecimalField
+from django.db.models.functions import Coalesce
 from itertools import chain
 
 from ..models import Product, ProductCategory, ProductTag, ProductKit
@@ -162,8 +163,14 @@ class ProductDetailView(LoginRequiredMixin, PermissionRequiredMixin, DetailView)
     permission_required = 'products.view_product'
 
     def get_queryset(self):
-        # Предзагрузка фотографий для избежания N+1 запросов
-        return super().get_queryset().prefetch_related('photos')
+        # Предзагрузка фотографий и аннотация остатков
+        total_available = Coalesce(Sum('stocks__quantity_available'), Value(0), output_field=DecimalField())
+        total_reserved = Coalesce(Sum('stocks__quantity_reserved'), Value(0), output_field=DecimalField())
+        return super().get_queryset().prefetch_related('photos').annotate(
+            total_available=total_available,
+            total_reserved=total_reserved,
+            total_free=total_available - total_reserved,
+        )
 
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
@@ -253,7 +260,14 @@ class CombinedProductListView(LoginRequiredMixin, PermissionRequiredMixin, ListV
         type_filter = self.request.GET.get('type', 'all')
         
         # Получаем товары и комплекты (только постоянные комплекты)
-        products = Product.objects.prefetch_related('categories', 'photos', 'tags')
+        # Аннотируем товары данными об остатках из агрегированной таблицы Stock
+        total_available = Coalesce(Sum('stocks__quantity_available'), Value(0), output_field=DecimalField())
+        total_reserved = Coalesce(Sum('stocks__quantity_reserved'), Value(0), output_field=DecimalField())
+        products = Product.objects.prefetch_related('categories', 'photos', 'tags').annotate(
+            total_available=total_available,
+            total_reserved=total_reserved,
+            total_free=total_available - total_reserved,
+        )
         kits = ProductKit.objects.filter(is_temporary=False).prefetch_related('categories', 'photos', 'tags')
 
         # Применяем фильтры