add page builder polish: utility blocks, templates, duplicate

New block types: spacer, divider, button/CTA, video embed (YouTube,
Vimeo with privacy-enhanced embeds, fallback for unknown URLs).

Page templates (blank, content, landing) shown when creating custom
pages. Duplicate page action on admin index with slug deduplication.

Fix block picker on shop edit sidebar being cut off on mobile by
accounting for bottom nav and making the grid scrollable.

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

test/berrypod_web/page_renderer_test.exs

@@ -231,6 +231,130 @@ defmodule BerrypodWeb.PageRendererTest do
     end
   end
 
+  describe "utility blocks" do
+    setup do
+      on_exit(fn ->
+        import Ecto.Query
+        Berrypod.Repo.delete_all(from p in Berrypod.Pages.Page, where: p.slug == "home")
+        Berrypod.Pages.PageCache.invalidate_all()
+      end)
+
+      :ok
+    end
+
+    test "spacer block renders with size" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [%{"id" => "blk_sp", "type" => "spacer", "settings" => %{"size" => "large"}}]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ ~s(class="block-spacer")
+      assert html =~ ~s(data-size="large")
+    end
+
+    test "divider block renders with style" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [%{"id" => "blk_dv", "type" => "divider", "settings" => %{"style" => "dots"}}]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ ~s(class="block-divider")
+      assert html =~ ~s(data-style="dots")
+    end
+
+    test "button block renders themed link" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [
+            %{
+              "id" => "blk_btn",
+              "type" => "button",
+              "settings" => %{
+                "text" => "Shop now",
+                "href" => "/collections/all",
+                "style" => "primary",
+                "alignment" => "centre"
+              }
+            }
+          ]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ "Shop now"
+      assert html =~ ~s(data-align="centre")
+      assert html =~ "themed-button"
+    end
+
+    test "video embed renders YouTube iframe" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [
+            %{
+              "id" => "blk_vid",
+              "type" => "video_embed",
+              "settings" => %{
+                "url" => "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
+                "caption" => "Demo video"
+              }
+            }
+          ]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ "youtube-nocookie.com/embed/dQw4w9WgXcQ"
+      assert html =~ "Demo video"
+      assert html =~ "video-embed"
+    end
+
+    test "video embed renders Vimeo iframe" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [
+            %{
+              "id" => "blk_vim",
+              "type" => "video_embed",
+              "settings" => %{"url" => "https://vimeo.com/123456789"}
+            }
+          ]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ "player.vimeo.com/video/123456789"
+    end
+
+    test "video embed shows fallback link for unknown URLs" do
+      {:ok, _} =
+        Pages.save_page("home", %{
+          title: "Home",
+          blocks: [
+            %{
+              "id" => "blk_unk",
+              "type" => "video_embed",
+              "settings" => %{"url" => "https://example.com/video", "caption" => "My video"}
+            }
+          ]
+        })
+
+      html = render_page("home", %{products: []})
+
+      assert html =~ "video-embed-fallback"
+      assert html =~ "My video"
+      refute html =~ "<iframe"
+    end
+  end
+
   describe "format_order_status/1" do
     test "maps status strings to display text" do
       assert PageRenderer.format_order_status("unfulfilled") == "Being prepared"