hide system events by default on activity page

Adds a toggle to show/hide internal system events (syncs, job failures,
abandoned cart creation) on the activity feed. Hidden by default so shop
owners only see actionable items. Toggle is ephemeral — resets on page load.

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

lib/berrypod/activity_log.ex

@@ -11,6 +11,11 @@ defmodule Berrypod.ActivityLog do
   alias Berrypod.Repo
   alias Berrypod.ActivityLog.Entry
 
+  @system_event_types ~w(sync.started sync.completed sync.failed job.exhausted abandoned_cart.created)
+
+  @doc "Returns true if the event type is internal system noise."
+  def system_event_type?(event_type), do: event_type in @system_event_types
+
   # ── Write ──
 
   @doc """
@@ -71,6 +76,7 @@ defmodule Berrypod.ActivityLog do
     * `:tab` - "all" (default) or "attention" (unresolved warnings/errors)
     * `:category` - "orders", "syncs", "emails", "carts", or nil for all
     * `:search` - order number substring search
+    * `:hide_system` - exclude system event types (default false)
 
   """
   def list_recent(opts \\ []) do
@@ -78,6 +84,7 @@ defmodule Berrypod.ActivityLog do
     |> order_by([a], desc: a.occurred_at)
     |> maybe_filter_tab(opts[:tab])
     |> maybe_filter_category(opts[:category])
+    |> maybe_hide_system(opts[:hide_system])
     |> maybe_search_order_number(opts[:search])
     |> Berrypod.Pagination.paginate(page: opts[:page], per_page: 50)
   end
@@ -165,6 +172,12 @@ defmodule Berrypod.ActivityLog do
 
   defp maybe_filter_category(query, _), do: query
 
+  defp maybe_hide_system(query, true) do
+    where(query, [a], a.event_type not in ^@system_event_types)
+  end
+
+  defp maybe_hide_system(query, _), do: query
+
   defp maybe_search_order_number(query, search) when is_binary(search) and search != "" do
     query
     |> join(:inner, [a], o in "orders", on: a.order_id == o.id)