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/admin_layout_hook.ex

@@ -5,7 +5,7 @@ defmodule BerrypodWeb.AdminLayoutHook do
   """
   import Phoenix.Component
 
-  alias Berrypod.Settings
+  alias Berrypod.{ActivityLog, Settings}
   alias Berrypod.Theme.{CSSCache, CSSGenerator}
 
   def on_mount(:assign_current_path, _params, _session, socket) do
@@ -22,6 +22,8 @@ defmodule BerrypodWeb.AdminLayoutHook do
           css
       end
 
+    if Phoenix.LiveView.connected?(socket), do: ActivityLog.subscribe()
+
     socket =
       socket
       |> assign(:current_path, "")
@@ -29,6 +31,7 @@ defmodule BerrypodWeb.AdminLayoutHook do
       |> assign(:email_configured, Berrypod.Mailer.email_configured?())
       |> assign(:theme_settings, theme_settings)
       |> assign(:generated_css, generated_css)
+      |> assign(:attention_count, ActivityLog.count_needing_attention())
       |> Phoenix.LiveView.attach_hook(:set_current_path, :handle_params, fn _params,
                                                                             uri,
                                                                             socket ->
@@ -37,6 +40,13 @@ defmodule BerrypodWeb.AdminLayoutHook do
          |> assign(:current_path, URI.parse(uri).path)
          |> assign(:site_live, Settings.site_live?())}
       end)
+      |> Phoenix.LiveView.attach_hook(:update_attention_count, :handle_info, fn
+        {:new_activity, _entry}, socket ->
+          {:cont, assign(socket, :attention_count, ActivityLog.count_needing_attention())}
+
+        _other, socket ->
+          {:cont, socket}
+      end)
 
     {:cont, socket}
   end