feat: Add cart store for catalog quantity sync

- Create Pinia cart store to manage cart state globally
- Sync quantity changes between catalog cards and cart sidebar
- Improve product card design with borders and hover effects
- Fix cart sync when updating quantity via minus button or input field

src/components/Purchase.vue

@@ -186,17 +186,17 @@
          clients: [],
          products: [],
      };
-   },
+    },
      created() {
-     this.fetchClients();
-     this.fetchProducts();
-     this.fetchPaymentMethods();
-   },
-   watch: {
-     group () {
-       this.drawer = false
+       this.fetchClients();
+       this.fetchProducts();
+       this.fetchPaymentMethods();
      },
-   },
+    watch: {
+      group () {
+        this.drawer = false
+      },
+    },
    beforeMount() {
       window.addEventListener('beforeunload', this.confirmLeave);
    },
@@ -228,8 +228,8 @@
        });
      },
    },
-   methods: {
-     openModal() {
+     methods: {
+       openModal() {
       this.$refs.customerModal.openModal();
      },
      onFormChange() {
@@ -307,25 +307,25 @@
      calculateSubtotal(line) {
        return line.unit_price * line.quantity;
      },
-     async submit() {
-       this.$refs.purchase.validate();
-         if (this.valid) {
-           this.api.createPurchase(this.purchase)
-               .then(data => {
-                 console.log('Compra enviada:', data);
-                 this.$router.push({
-                   path: "/summary_purchase",
-                   query : {id: parseInt(data.id)}
-                 });
-               })
-           .catch(error => console.error('Error al enviarl la compra:', error));
-       } else {
-         this.show_alert_purchase = true;
-           setTimeout(() => {
-             this.show_alert_purchase = false;
-           }, 4000);
-       }
-     },
+      async submit() {
+        this.$refs.purchase.validate();
+          if (this.valid) {
+             this.api.createPurchase(this.purchase)
+                 .then(data => {
+                   console.log('Compra enviada:', data);
+                   this.$router.push({
+                    path: "/summary_purchase",
+                    query : {id: parseInt(data.id)}
+                  });
+                })
+            .catch(error => console.error('Error al enviarl la compra:', error));
+        } else {
+          this.show_alert_purchase = true;
+            setTimeout(() => {
+              this.show_alert_purchase = false;
+            }, 4000);
+        }
+      },
      navigate(route) {
        this.$router.push(route);
      },