integrate R module and add url editor ui

Replaces hardcoded paths with R module throughout:
- Shop components: layout nav, cart, product links
- Controllers: cart, checkout, contact, seo, order lookup
- Shop pages: collection, product, search, checkout success, etc.
- Site context: nav item url resolution

Admin URL management:
- Settings page: prefix editor with validation feedback
- Page renderer: url_editor component for page URLs
- CSS for url editor styling

Test updates for cache isolation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/berrypod_web/live/shop/pages/collection.ex

@@ -7,6 +7,7 @@ defmodule BerrypodWeb.Shop.Pages.Collection do
   import Phoenix.LiveView, only: [push_patch: 2, push_navigate: 2, put_flash: 3]
 
   alias Berrypod.{Pages, Pagination, Products}
+  alias BerrypodWeb.R
 
   @sort_options [
     {"featured", "Featured"},
@@ -29,6 +30,11 @@ defmodule BerrypodWeb.Shop.Pages.Collection do
     {:noreply, socket}
   end
 
+  # When accessed via custom URL (e.g. /shop) without a collection slug, show all products
+  def handle_params(params, uri, socket) when not is_map_key(params, "slug") do
+    handle_params(Map.put(params, "slug", "all"), uri, socket)
+  end
+
   def handle_params(%{"slug" => slug} = params, _uri, socket) do
     sort = params["sort"] || "featured"
     page_num = Pagination.parse_page(params)
@@ -39,7 +45,7 @@ defmodule BerrypodWeb.Shop.Pages.Collection do
           socket
           |> assign(:page_title, title)
           |> assign(:page_description, collection_description(title))
-          |> assign(:og_url, BerrypodWeb.Endpoint.url() <> "/collections/#{slug}")
+          |> assign(:og_url, R.url(R.collection(slug)))
           |> assign(:collection_title, title)
           |> assign(:collection_slug, slug)
           |> assign(:current_category, category)
@@ -53,7 +59,7 @@ defmodule BerrypodWeb.Shop.Pages.Collection do
         socket =
           socket
           |> put_flash(:error, "Collection not found")
-          |> push_navigate(to: "/collections/all")
+          |> push_navigate(to: R.collection("all"))
 
         {:noreply, socket}
     end
@@ -67,7 +73,7 @@ defmodule BerrypodWeb.Shop.Pages.Collection do
         category -> category.slug
       end
 
-    {:noreply, push_patch(socket, to: "/collections/#{slug}?sort=#{sort}")}
+    {:noreply, push_patch(socket, to: R.collection(slug) <> "?sort=#{sort}")}
   end
 
   def handle_event(_event, _params, _socket), do: :cont