add provider sync enhancements for product lifecycle

- add discontinued status to products (soft-delete when removed from provider)
- add availability helpers to variants (available/out_of_stock/discontinued)
- add detailed sync audit logging (product created/updated/discontinued)
- add cost change detection with threshold alerts (5% warning, 20% critical)
- update cart to show unavailable items with appropriate messaging
- block checkout when cart contains unavailable items
- show discontinued badge on product pages

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

lib/berrypod_web/components/shop_components/cart.ex

@@ -45,10 +45,18 @@ defmodule BerrypodWeb.ShopComponents.Cart do
   attr :stripe_connected, :boolean, default: true
 
   def cart_drawer(assigns) do
+    # Check if any cart items are unavailable (out of stock or discontinued)
+    has_unavailable_items =
+      Enum.any?(assigns.cart_items, fn item ->
+        Map.get(item, :product_discontinued) == true or Map.get(item, :is_available) == false
+      end)
+
     assigns =
-      assign_new(assigns, :display_total, fn ->
+      assigns
+      |> assign_new(:display_total, fn ->
         assigns.total || assigns.subtotal || "£0.00"
       end)
+      |> assign(:has_unavailable_items, has_unavailable_items)
 
     ~H"""
     <%!-- Screen reader announcements for cart changes --%>
@@ -142,6 +150,13 @@ defmodule BerrypodWeb.ShopComponents.Cart do
               Checkout
             </button>
             <p class="cart-drawer-notice">Checkout isn't available yet.</p>
+          <% @has_unavailable_items -> %>
+            <button type="button" disabled class="cart-drawer-checkout">
+              Checkout
+            </button>
+            <p class="cart-drawer-notice">
+              Remove unavailable items to checkout.
+            </p>
           <% true -> %>
             <form action="/checkout" method="post">
               <input type="hidden" name="_csrf_token" value={Phoenix.Controller.get_csrf_token()} />
@@ -212,8 +227,14 @@ defmodule BerrypodWeb.ShopComponents.Cart do
           </p>
         <% end %>
 
-        <p :if={Map.get(@item, :is_available) == false} class="cart-item-unavailable">
-          This item is currently unavailable
+        <p :if={Map.get(@item, :product_discontinued)} class="cart-item-unavailable">
+          This product is no longer available
+        </p>
+        <p
+          :if={!Map.get(@item, :product_discontinued) && Map.get(@item, :is_available) == false}
+          class="cart-item-unavailable"
+        >
+          This option is currently out of stock
         </p>
 
         <div class="cart-item-actions">
@@ -457,6 +478,7 @@ defmodule BerrypodWeb.ShopComponents.Cart do
   attr :available_countries, :list, default: []
   attr :mode, :atom, default: :live
   attr :stripe_connected, :boolean, default: true
+  attr :has_unavailable_items, :boolean, default: false
 
   def order_summary(assigns) do
     assigns =
@@ -516,6 +538,17 @@ defmodule BerrypodWeb.ShopComponents.Cart do
           >
             Continue shopping
           </.shop_link_outline>
+        <% @has_unavailable_items -> %>
+          <.shop_button disabled class="order-summary-checkout">
+            Checkout
+          </.shop_button>
+          <p class="order-summary-notice">Remove unavailable items to checkout.</p>
+          <.shop_link_outline
+            href="/collections/all"
+            class="order-summary-continue"
+          >
+            Continue shopping
+          </.shop_link_outline>
         <% true -> %>
           <form action="/checkout" method="post" class="order-summary-checkout-form">
             <input type="hidden" name="_csrf_token" value={Phoenix.Controller.get_csrf_token()} />