Redesign cart and collections, fix product pagination

- Cart drawer: single-column layout matching the site — no bag icon,
  no dividers, square images, tighter type, discount code form,
  estimated total, and a Go to Checkout button
- Cart: per-line loading state so one row's update no longer disables
  every other row or the checkout button
- Discounts: cartDiscountCodesUpdate mutation plus discountCodes on the
  cart fragment, wired to an applyDiscountCode store action
- Products: fix "load more" returning the same first page — the query
  now takes an `after` cursor and getProductsPage exposes pageInfo
- Collections: cards match the product cards (no border, radius, blurb,
  or CTA row) at 4-up on desktop and 2-up on mobile; section headers
  match the products section
- Shop Pay: cart permalink with payment=shop_pay instead of the hosted
  shop-js element
- Buttons converted to the shadcn Button component throughout
- PDP: swipeable image carousel with dots on mobile, sticky info column,
  colour swatches never fall back to variant photos
- Rename the store from Stride to Shop; larger header wordmark

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jWbNNJLksC1QG8z8845FX

hooks/use-shopify-products.ts

@@ -81,11 +81,19 @@ export interface Product {
 
 interface UseProductsOptions {
   first?: number;
+  /** Cursor from a previous page's `endCursor`; omit for the first page. */
+  after?: string | null;
   query?: string;
   sortKey?: 'BEST_SELLING' | 'CREATED_AT' | 'PRICE' | 'TITLE';
   reverse?: boolean;
 }
 
+export interface ProductsPage {
+  products: Product[];
+  hasNextPage: boolean;
+  endCursor: string | null;
+}
+
 interface UseProductsReturn {
   products: Product[];
   loading: boolean;
@@ -94,18 +102,33 @@ interface UseProductsReturn {
 }
 
 // Fetch multiple products
-export async function getProducts({
+export async function getProducts(
+  options: UseProductsOptions = {}
+): Promise<Product[]> {
+  const { products } = await getProductsPage(options);
+  return products;
+}
+
+// Same fetch, but keeps the cursor so callers can page through the catalogue.
+export async function getProductsPage({
   first = 20,
+  after = null,
   query = '',
   sortKey = 'BEST_SELLING',
   reverse = false,
-}: UseProductsOptions = {}): Promise<Product[]> {
+}: UseProductsOptions = {}): Promise<ProductsPage> {
   const response = await shopifyFetch({
     query: GET_PRODUCTS_QUERY,
-    variables: { first, query, sortKey, reverse },
+    variables: { first, after, query, sortKey, reverse },
   });
 
-  return response.data.products.edges.map((edge: { node: Product }) => edge.node);
+  const { edges, pageInfo } = response.data.products;
+
+  return {
+    products: edges.map((edge: { node: Product }) => edge.node),
+    hasNextPage: Boolean(pageInfo?.hasNextPage),
+    endCursor: pageInfo?.endCursor ?? null,
+  };
 }
 
 // Fetch a single product by handle