Add: CartProvider

lib/pages/detail.dart

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:gymlink_module_web/components/app_bar.dart';
 import 'package:gymlink_module_web/components/heading.dart';
+import 'package:gymlink_module_web/providers/cart.dart';
 import 'package:gymlink_module_web/tools/prefs.dart';
+import 'package:provider/provider.dart';
 
 //TODO: Сделать получение инфы через объект
 class DetailPage extends StatefulWidget {
@@ -67,6 +69,9 @@ class _DetailPageState extends State<DetailPage> {
             isInCart = true;
             quantity = 1;
           });
+          if (mounted) {
+            context.read<CartProvider>().updateCartLength();
+          }
         },
         style: ElevatedButton.styleFrom(
             backgroundColor: Theme.of(context).primaryColor,
@@ -93,6 +98,9 @@ class _DetailPageState extends State<DetailPage> {
                   quantity = 0;
                 }
               });
+              if (mounted) {
+                context.read<CartProvider>().updateCartLength();
+              }
             },
           ),
           const SizedBox(width: 10),