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/admin/product_show.ex

@@ -4,6 +4,7 @@ defmodule BerrypodWeb.Admin.ProductShow do
   alias Berrypod.Products
   alias Berrypod.Products.{Product, ProductImage, ProductVariant}
   alias Berrypod.Cart
+  alias BerrypodWeb.R
 
   @impl true
   def mount(%{"id" => id}, _session, socket) do
@@ -109,7 +110,7 @@ defmodule BerrypodWeb.Admin.ProductShow do
           <.icon name="hero-arrow-top-right-on-square-mini" class="size-4" />
         </.external_link>
         <.link
-          navigate={~p"/products/#{@product.slug}"}
+          navigate={R.product(@product.slug)}
           class="admin-btn admin-btn-ghost admin-btn-sm"
         >
           View on shop <.icon name="hero-arrow-top-right-on-square-mini" class="size-4" />

lib/berrypod_web/live/admin/settings.ex

@@ -18,7 +18,15 @@ defmodule BerrypodWeb.Admin.Settings do
      |> assign(:from_address_status, :idle)
      |> assign(:signing_secret_status, :idle)
      |> assign_stripe_state()
-     |> assign_products_state()}
+     |> assign_products_state()
+     |> assign_url_prefixes()}
+  end
+
+  defp assign_url_prefixes(socket) do
+    socket
+    |> assign(:products_prefix, Settings.get_url_prefix(:products))
+    |> assign(:collections_prefix, Settings.get_url_prefix(:collections))
+    |> assign(:prefix_status, :idle)
   end
 
   # -- Stripe assigns --
@@ -117,6 +125,51 @@ defmodule BerrypodWeb.Admin.Settings do
     end
   end
 
+  # -- Events: URL prefixes --
+
+  def handle_event("change_prefix", _params, socket) do
+    {:noreply, assign(socket, :prefix_status, :idle)}
+  end
+
+  def handle_event("save_prefixes", %{"prefixes" => params}, socket) do
+    products_prefix = params["products"] || ""
+    collections_prefix = params["collections"] || ""
+
+    errors = []
+
+    # Update products prefix if changed
+    errors =
+      if products_prefix != socket.assigns.products_prefix do
+        case Settings.update_url_prefix(:products, products_prefix) do
+          {:ok, _} -> errors
+          {:error, reason} -> [{:products, reason} | errors]
+        end
+      else
+        errors
+      end
+
+    # Update collections prefix if changed
+    errors =
+      if collections_prefix != socket.assigns.collections_prefix do
+        case Settings.update_url_prefix(:collections, collections_prefix) do
+          {:ok, _} -> errors
+          {:error, reason} -> [{:collections, reason} | errors]
+        end
+      else
+        errors
+      end
+
+    if errors == [] do
+      {:noreply,
+       socket
+       |> assign_url_prefixes()
+       |> assign(:prefix_status, :saved)}
+    else
+      error_message = format_prefix_errors(errors)
+      {:noreply, put_flash(socket, :error, error_message)}
+    end
+  end
+
   # -- Events: Stripe --
 
   def handle_event("connect_stripe", %{"stripe" => %{"api_key" => api_key}}, socket) do
@@ -388,6 +441,67 @@ defmodule BerrypodWeb.Admin.Settings do
           </form>
         </div>
       </section>
+
+      <%!-- URL prefixes --%>
+      <section class="admin-section">
+        <h2 class="admin-section-title">URL prefixes</h2>
+        <p class="admin-section-desc">
+          Customise the URL structure for products and collections.
+          Old URLs will automatically redirect to the new ones.
+        </p>
+        <div class="admin-section-body">
+          <form
+            phx-change="change_prefix"
+            phx-submit="save_prefixes"
+            class="admin-stack"
+          >
+            <div class="admin-row admin-row-lg">
+              <label class="admin-label admin-label-inline" for="prefix-products">
+                Products
+              </label>
+              <div class="admin-row admin-row-sm">
+                <span class="admin-text-secondary">/</span>
+                <.input
+                  name="prefixes[products]"
+                  id="prefix-products"
+                  value={@products_prefix}
+                  placeholder="products"
+                  pattern="[a-z0-9-]+"
+                />
+                <span class="admin-text-secondary">/</span>
+                <span class="admin-text-tertiary">product-slug</span>
+              </div>
+            </div>
+
+            <div class="admin-row admin-row-lg">
+              <label class="admin-label admin-label-inline" for="prefix-collections">
+                Collections
+              </label>
+              <div class="admin-row admin-row-sm">
+                <span class="admin-text-secondary">/</span>
+                <.input
+                  name="prefixes[collections]"
+                  id="prefix-collections"
+                  value={@collections_prefix}
+                  placeholder="collections"
+                  pattern="[a-z0-9-]+"
+                />
+                <span class="admin-text-secondary">/</span>
+                <span class="admin-text-tertiary">collection-slug</span>
+              </div>
+            </div>
+
+            <p class="admin-help-text">
+              Use only lowercase letters, numbers, and hyphens.
+            </p>
+
+            <div class="admin-form-actions-sm">
+              <.button phx-disable-with="Saving...">Save</.button>
+              <.inline_feedback status={@prefix_status} />
+            </div>
+          </form>
+        </div>
+      </section>
     </div>
     """
   end
@@ -639,4 +753,20 @@ defmodule BerrypodWeb.Admin.Settings do
       true -> "#{div(diff, 86400)} days ago"
     end
   end
+
+  defp format_prefix_errors(errors) do
+    Enum.map_join(errors, "; ", fn {field, reason} ->
+      field_name = if field == :products, do: "Products", else: "Collections"
+
+      message =
+        case reason do
+          :empty_prefix -> "can't be blank"
+          :invalid_format -> "must contain only letters, numbers, and hyphens"
+          :reserved_prefix -> "is reserved"
+          _ -> "is invalid"
+        end
+
+      "#{field_name} prefix #{message}"
+    end)
+  end
 end