add pagination across all admin and shop views

URL-based offset pagination with ?page=N for bookmarkable pages.
Admin views use push_patch, shop collection uses navigate links.
Responsive on mobile with horizontal-scroll tables and stacking
pagination controls. Includes dev seed script for testing.

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

test/berrypod/newsletter/notifier_test.exs

@@ -84,7 +84,8 @@ defmodule Berrypod.Newsletter.NotifierTest do
 
   describe "deliver_test/2" do
     test "sends test email with [Test] prefix in subject" do
-      campaign = campaign_fixture(subject: "Big launch", body: "Preview this!\n\n{{unsubscribe_url}}")
+      campaign =
+        campaign_fixture(subject: "Big launch", body: "Preview this!\n\n{{unsubscribe_url}}")
 
       assert {:ok, _} = Notifier.deliver_test(campaign, "admin@example.com")