feat: add cart and product pages, quantity controls, and first-visit development notice

components/CartPersistence.tsx

@@ -0,0 +1,46 @@
+'use client';
+
+import {useEffect} from 'react';
+import {useStore} from 'react-redux';
+import type {AppStore} from '@/store/store';
+import type {CartItem} from '@/types/domain';
+import {restoreCart} from '@/store/cartSlice';
+import {content} from '@/data/content';
+
+const STORAGE_KEY = 'rm-cart';
+const useAppStore = useStore.withTypes<AppStore>();
+
+export default function CartPersistence() {
+    const store = useAppStore();
+
+    useEffect(() => {
+        try {
+            const saved: unknown = JSON.parse(localStorage.getItem(STORAGE_KEY) ?? '[]');
+            if (Array.isArray(saved)) {
+                const items: CartItem[] = [];
+                for (const entry of saved) {
+                    if (!entry || typeof entry !== 'object' || typeof entry.id !== 'string'
+                        || !Number.isSafeInteger(entry.qty) || entry.qty < 1) continue;
+                    const machine = content.fa.machines.find(item => item.id === entry.id);
+                    if (!machine || items.some(item => item.id === machine.id)) continue;
+                    // Restore identifiers and quantities; use current catalog prices and images.
+                    items.push({id: machine.id, name: machine.name, image: machine.image,
+                        priceNumeric: machine.priceNumeric, priceLabel: machine.priceLabel, qty: entry.qty});
+                }
+                store.dispatch(restoreCart(items));
+            }
+        } catch {
+            // Invalid or unavailable storage must not prevent shopping.
+        }
+
+        return store.subscribe(() => {
+            try {
+                localStorage.setItem(STORAGE_KEY, JSON.stringify(store.getState().cart.items.map(({id, qty}) => ({id, qty}))));
+            } catch {
+                // Keep the in-memory cart usable when storage is full or disabled.
+            }
+        });
+    }, [store]);
+
+    return null;
+}