add no-JS fallback for cart country selector

The delivery country form now has action="/cart/country" with a
noscript submit button. Without JS, changing the country and clicking
Update POSTs to a new CartController.update_country action that saves
the country to session and redirects back to /cart.

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

lib/berrypod_web/components/shop_components/cart.ex

@@ -403,7 +403,8 @@ defmodule BerrypodWeb.ShopComponents.Cart do
       <span class="delivery-line-label">
         Delivery to
         <%= if @available_countries != [] and @mode != :preview do %>
-          <form phx-change="change_country">
+          <form action="/cart/country" method="post" phx-change="change_country">
+            <input type="hidden" name="_csrf_token" value={Phoenix.Controller.get_csrf_token()} />
             <select
               name="country"
               class="delivery-select"
@@ -413,6 +414,9 @@ defmodule BerrypodWeb.ShopComponents.Cart do
                 <option value={code} selected={code == @country_code}>{name}</option>
               <% end %>
             </select>
+            <noscript>
+              <button type="submit" class="themed-button delivery-country-submit">Update</button>
+            </noscript>
           </form>
         <% else %>
           <span>{Berrypod.Shipping.country_name(@country_code)}</span>

lib/berrypod_web/controllers/cart_controller.ex

@@ -74,6 +74,19 @@ defmodule BerrypodWeb.CartController do
     |> redirect(to: ~p"/cart")
   end
 
+  @doc """
+  Updates delivery country via form POST (no-JS fallback).
+  """
+  def update_country(conn, %{"country" => code}) when is_binary(code) and code != "" do
+    conn
+    |> put_session("country_code", code)
+    |> redirect(to: ~p"/cart")
+  end
+
+  def update_country(conn, _params) do
+    redirect(conn, to: ~p"/cart")
+  end
+
   defp parse_quantity(str) when is_binary(str) do
     case Integer.parse(str) do
       {qty, _} when qty > 0 -> qty

lib/berrypod_web/router.ex

@@ -97,6 +97,7 @@ defmodule BerrypodWeb.Router do
     post "/cart/add", CartController, :add
     post "/cart/remove", CartController, :remove
     post "/cart/update", CartController, :update_item
+    post "/cart/country", CartController, :update_country
   end
 
   # Health check (no auth, no theme loading — for load balancers and uptime monitors)