add activity log with order timeline and global feed

Single activity_log table powering two views: chronological timeline
on each order detail page (replacing the old fulfilment card) and a
global feed at /admin/activity with tabs, category filters, search,
and pagination. Real-time via PubSub — new entries appear instantly,
nav badge updates across all admin pages.

Instrumented across all event points: Stripe webhooks, order notifier,
submission worker, fulfilment status worker, product sync worker, and
Oban exhausted-job telemetry. Contextual action buttons (retry
submission, retry sync, dismiss) with Oban unique constraints to
prevent double-enqueue. 90-day pruning via cron.

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

lib/berrypod_web/controllers/stripe_webhook_controller.ex

@@ -1,7 +1,7 @@
 defmodule BerrypodWeb.StripeWebhookController do
   use BerrypodWeb, :controller
 
-  alias Berrypod.Orders
+  alias Berrypod.{ActivityLog, Orders}
   alias Berrypod.Orders.{OrderNotifier, OrderSubmissionWorker}
 
   require Logger
@@ -69,6 +69,17 @@ defmodule BerrypodWeb.StripeWebhookController do
           {:order_paid, order}
         )
 
+        ActivityLog.log_event(
+          "order.created",
+          "Order placed — #{Berrypod.Cart.format_price(order.total)} via Stripe",
+          order_id: order.id,
+          payload: %{
+            total: order.total,
+            currency: order.currency,
+            payment_intent: payment_intent_id
+          }
+        )
+
         OrderNotifier.deliver_order_confirmation(order)
 
         # Submit to fulfilment provider
@@ -138,6 +149,14 @@ defmodule BerrypodWeb.StripeWebhookController do
     case Orders.create_abandoned_cart(attrs) do
       {:ok, cart} ->
         Berrypod.Orders.AbandonedCartEmailWorker.enqueue(cart.id)
+
+        ActivityLog.log_event(
+          "abandoned_cart.created",
+          "Abandoned cart — #{email}, #{Berrypod.Cart.format_price(order.total)}",
+          order_id: order.id,
+          payload: %{email: email, total: order.total}
+        )
+
         Logger.info("Abandoned cart recorded for #{email}, recovery email scheduled")
 
       {:error, reason} ->