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/controllers/order_lookup_controller.ex

@@ -19,7 +19,7 @@ defmodule BerrypodWeb.OrderLookupController do
         :error,
         "No orders found for that address. Make sure you use the same email you checked out with."
       )
-      |> redirect(to: ~p"/contact")
+      |> redirect(to: R.contact())
     else
       token = generate_token(email)
       link = BerrypodWeb.Endpoint.url() <> ~p"/orders/verify/#{token}"
@@ -30,14 +30,14 @@ defmodule BerrypodWeb.OrderLookupController do
         :info,
         "We've sent a link to your email address. It'll expire after an hour."
       )
-      |> redirect(to: ~p"/contact")
+      |> redirect(to: R.contact())
     end
   end
 
   def lookup(conn, _params) do
     conn
     |> put_flash(:error, "Please enter your email address.")
-    |> redirect(to: ~p"/contact")
+    |> redirect(to: R.contact())
   end
 
   def verify(conn, %{"token" => token}) do
@@ -45,17 +45,17 @@ defmodule BerrypodWeb.OrderLookupController do
       {:ok, email} ->
         conn
         |> put_session(:order_lookup_email, email)
-        |> redirect(to: ~p"/orders")
+        |> redirect(to: R.orders())
 
       {:error, :expired} ->
         conn
         |> put_flash(:error, "That link has expired. Please request a new one.")
-        |> redirect(to: ~p"/contact")
+        |> redirect(to: R.contact())
 
       {:error, _} ->
         conn
         |> put_flash(:error, "That link is invalid.")
-        |> redirect(to: ~p"/contact")
+        |> redirect(to: R.contact())
     end
   end