wire collection, PDP, cart, and search pages to page renderer

Stage 4 of the page builder: all shop pages now render via
PageRenderer instead of inline templates or PageTemplates.

- Collection: full filter bar moved to renderer (category pills,
  sort dropdown, CollectionFilters hook, empty state)
- PDP: related_products and reviews loaded via block data loaders
  instead of manual queries
- Cart: page definition loaded in mount, subtotal computed in render
- Search: page definition loaded in mount, handle_params unchanged
- Added Phoenix.VerifiedRoutes to PageRenderer for ~p sigil
- Net -55 lines (128 added, 183 removed)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/berrypod_web/page_renderer.ex

@@ -10,6 +10,11 @@ defmodule BerrypodWeb.PageRenderer do
   use Phoenix.Component
   use BerrypodWeb.ShopComponents
 
+  use Phoenix.VerifiedRoutes,
+    endpoint: BerrypodWeb.Endpoint,
+    router: BerrypodWeb.Router,
+    statics: BerrypodWeb.static_paths()
+
   alias Berrypod.Cart
 
   # ── Public API ──────────────────────────────────────────────────
@@ -263,14 +268,85 @@ defmodule BerrypodWeb.PageRenderer do
   end
 
   defp render_block(%{block: %{"type" => "filter_bar"}} = assigns) do
+    current_slug =
+      case assigns[:current_category] do
+        :sale -> "sale"
+        nil -> nil
+        cat -> cat.slug
+      end
+
+    assigns =
+      assigns
+      |> assign(:current_slug, current_slug)
+      |> assign(:current_sort, assigns[:current_sort] || "featured")
+      |> assign(:sort_options, assigns[:sort_options] || [])
+
     ~H"""
     <div class="page-container">
-      <.filter_bar categories={assigns[:categories] || []} />
+      <div class="filter-bar">
+        <nav
+          aria-label="Collection filters"
+          id="collection-filters"
+          phx-hook="CollectionFilters"
+          class="collection-filters"
+        >
+          <ul class="collection-filter-pills">
+            <li>
+              <.link
+                navigate={collection_path("all", @current_sort)}
+                aria-current={@current_slug == nil && "page"}
+                class={["collection-filter-pill", @current_slug == nil && "active"]}
+              >
+                All
+              </.link>
+            </li>
+            <li>
+              <.link
+                navigate={collection_path("sale", @current_sort)}
+                aria-current={@current_slug == "sale" && "page"}
+                class={["collection-filter-pill", @current_slug == "sale" && "active"]}
+              >
+                Sale
+              </.link>
+            </li>
+            <%= for category <- assigns[:categories] || [] do %>
+              <li>
+                <.link
+                  navigate={collection_path(category.slug, @current_sort)}
+                  aria-current={@current_slug == category.slug && "page"}
+                  class={["collection-filter-pill", @current_slug == category.slug && "active"]}
+                >
+                  {category.name}
+                </.link>
+              </li>
+            <% end %>
+          </ul>
+        </nav>
+
+        <form
+          action={~p"/collections/#{@current_slug || "all"}"}
+          method="get"
+          phx-change="sort_changed"
+        >
+          <.shop_select
+            name="sort"
+            options={@sort_options}
+            selected={@current_sort}
+            aria-label="Sort products"
+          />
+          <noscript>
+            <button type="submit" class="themed-button collection-sort-submit">Sort</button>
+          </noscript>
+        </form>
+      </div>
     </div>
     """
   end
 
   defp render_block(%{block: %{"type" => "product_grid"}} = assigns) do
+    show_category = assigns[:current_category] in [nil, :sale]
+    assigns = assign(assigns, :show_category, show_category)
+
     ~H"""
     <div class="page-container">
       <.product_grid theme_settings={@theme_settings}>
@@ -280,10 +356,19 @@ defmodule BerrypodWeb.PageRenderer do
             theme_settings={@theme_settings}
             mode={@mode}
             variant={:default}
-            show_category={true}
+            show_category={@show_category}
           />
         <% end %>
       </.product_grid>
+
+      <%= if (assigns[:products] || []) == [] do %>
+        <div class="collection-empty">
+          <p>No products found in this collection.</p>
+          <.link navigate={~p"/collections/all"} class="collection-empty-link">
+            View all products
+          </.link>
+        </div>
+      <% end %>
     </div>
     """
   end
@@ -722,6 +807,7 @@ defmodule BerrypodWeb.PageRenderer do
   def page_main_class("orders"), do: "page-container orders-main"
   def page_main_class("order_detail"), do: "page-container order-detail-main"
   def page_main_class("error"), do: "error-main"
+  def page_main_class("collection"), do: nil
   def page_main_class("pdp"), do: "page-container"
   def page_main_class("search"), do: "page-container"
   def page_main_class("about"), do: "content-page"
@@ -767,6 +853,9 @@ defmodule BerrypodWeb.PageRenderer do
 
   defp breadcrumb_items(_), do: []
 
+  defp collection_path(slug, "featured"), do: ~p"/collections/#{slug}"
+  defp collection_path(slug, sort), do: ~p"/collections/#{slug}?sort=#{sort}"
+
   # Reuse from PageTemplates
   def format_order_status("unfulfilled"), do: "Being prepared"
   def format_order_status("submitted"), do: "Sent to printer"