add SEO enhancements: OG images, meta robots, FAQ block, image sitemap

- Per-page SEO controls: meta robots directives, focus keyword, OG image
- Site-wide default OG image in admin settings
- FAQ block type with FAQPage JSON-LD schema
- Enhanced Organization JSON-LD with business info, contact, address
- Image sitemap with product images
- SEO preview panel with Google/social card mockups
- SEO checklist with real-time scoring
- Business info section in site editor
- GSC integration scaffolding (OAuth, client, cache)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/berrypod_web/page_editor_hook.ex

@@ -1285,6 +1285,11 @@ defmodule BerrypodWeb.PageEditorHook do
     handle_theme_action("remove_header", %{}, socket)
   end
 
+  defp handle_site_action("update_business_info", %{"business_info" => info_params}, socket) do
+    socket = handle_business_info_update(socket, info_params)
+    {:halt, socket}
+  end
+
   # Catch-all for unknown site actions
   defp handle_site_action(_action, _params, socket), do: {:halt, socket}
 
@@ -1334,6 +1339,20 @@ defmodule BerrypodWeb.PageEditorHook do
     |> assign(:site_dirty, SiteEditorState.dirty?(state))
   end
 
+  defp handle_business_info_update(socket, params) do
+    state = socket.assigns.site_state
+
+    # Update each business info field
+    state =
+      Enum.reduce(params, state, fn {key, value}, acc ->
+        SiteEditorState.put_business_info(acc, key, value)
+      end)
+
+    socket
+    |> assign(:site_state, state)
+    |> assign(:site_dirty, SiteEditorState.dirty?(state))
+  end
+
   # Helper to update site state and compute dirty flag
   defp update_site_state(socket, update_fn) do
     state = socket.assigns.site_state