Add product pagination and enable BestBuy

Implement client-side pagination for the products grid: add PRODUCTS_PER_PAGE, currentProductPage, offset in /products requests, renderPagination(), and changeProductPage() (with smooth scroll). Reset page when filters or event filters change and render empty-state pagination. Add pagination container to the template and styles for pagination buttons and info. Also enable "bestbuy" in SITES_ENABLED in config.py and add a taskkill line to .claude/settings.local.json for closing stray python.exe processes.

dashboard/templates/index.html

@@ -110,6 +110,7 @@
         <div class="products-grid" id="productsGrid">
           <div class="loading">Loading products...</div>
         </div>
+        <div id="productsPagination"></div>
       </section>
 
       <!-- Analytics Page -->