add contextual prompts for skipped setup steps

Disable checkout when Stripe isn't connected (cart drawer, cart page,
and early guard in checkout controller to prevent orphaned orders).
Show amber warning on order detail when email isn't configured.
Fix pre-existing missing vertical spacing between page blocks.

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

lib/berrypod_web/live/admin/order_show.ex

@@ -1,7 +1,7 @@
 defmodule BerrypodWeb.Admin.OrderShow do
   use BerrypodWeb, :live_view
 
-  alias Berrypod.{ActivityLog, Orders}
+  alias Berrypod.{ActivityLog, Mailer, Orders}
   alias Berrypod.Cart
 
   @impl true
@@ -25,6 +25,7 @@ defmodule BerrypodWeb.Admin.OrderShow do
           |> assign(:page_title, order.order_number)
           |> assign(:order, order)
           |> assign(:timeline, timeline)
+          |> assign(:email_configured, Mailer.email_configured?())
 
         {:ok, socket}
     end
@@ -48,6 +49,25 @@ defmodule BerrypodWeb.Admin.OrderShow do
       </div>
     </.header>
 
+    <div :if={!@email_configured} class="admin-callout-warning admin-card-spaced">
+      <div class="admin-callout-warning-body">
+        <span class="admin-callout-warning-icon">
+          <.icon name="hero-exclamation-triangle" class="size-5" />
+        </span>
+        <div>
+          <p class="admin-callout-warning-title">
+            Order confirmation emails aren't being sent
+          </p>
+          <p class="admin-callout-warning-desc">
+            Set up an email provider to send order confirmations and shipping updates automatically.
+            <.link navigate={~p"/admin/settings/email"} class="admin-link">
+              Set up email &rarr;
+            </.link>
+          </p>
+        </div>
+      </div>
+    </div>
+
     <div class="admin-grid order-detail-grid">
       <%!-- order info --%>
       <div class="admin-card">