Zastosowanie wszystkich poprawek UI i logiki kalkulatora

lib/compare-store.ts

@@ -0,0 +1,35 @@
+import { create } from 'zustand';
+
+interface CompareItem {
+  slug: string;
+  name: string;
+  brand: string;
+  price: number | null;
+  image: string;
+  specs: Record<string, string>;
+}
+
+interface CompareState {
+  items: CompareItem[];
+  addItem: (item: CompareItem) => void;
+  removeItem: (slug: string) => void;
+  clearAll: () => void;
+  isAdded: (slug: string) => boolean;
+}
+
+export const useCompareStore = create<CompareState>()((set, get) => ({
+  items: [],
+
+  addItem: (item) => {
+    const { items } = get();
+    if (items.length >= 3 || items.find((i) => i.slug === item.slug)) return;
+    set({ items: [...items, item] });
+  },
+
+  removeItem: (slug) =>
+    set((state) => ({ items: state.items.filter((i) => i.slug !== slug) })),
+
+  clearAll: () => set({ items: [] }),
+
+  isAdded: (slug) => get().items.some((i) => i.slug === slug),
+}));