add Site context with social links editor and site-wide settings

- Add Site context for managing site-wide content (social links, nav items,
  announcement bar, footer content)
- Add SocialLink schema with URL normalization and platform auto-detection
  supporting 40+ platforms via host and 25+ via URI scheme
- Add NavItem schema for header/footer navigation (editor UI coming next)
- Add SiteEditor component with collapsible sections for each content type
- Wire social links card block and footer to use database data
- Filter empty URLs from display in shop components
- Add DetailsPreserver hook to preserve collapsible section state
- Add comprehensive tests for Site context and SocialLink functions
- Remove unused helper functions from onboarding to fix compiler warnings
- Move sync_edit_url_param helper to group handle_editor_event clauses

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

lib/berrypod_web/theme_hook.ex

@@ -14,7 +14,7 @@ defmodule BerrypodWeb.ThemeHook do
 
   import Phoenix.Component, only: [assign: 3]
 
-  alias Berrypod.{Products, Settings, Media}
+  alias Berrypod.{Products, Settings, Site, Media}
   alias Berrypod.Theme.{CSSCache, CSSGenerator}
 
   @default_header_nav [
@@ -67,8 +67,12 @@ defmodule BerrypodWeb.ThemeHook do
         :is_admin,
         !!(socket.assigns[:current_scope] && socket.assigns.current_scope.user)
       )
-      |> assign(:header_nav_items, load_nav("header_nav", @default_header_nav))
-      |> assign(:footer_nav_items, load_nav("footer_nav", @default_footer_nav))
+      |> assign(:header_nav_items, load_header_nav())
+      |> assign(:footer_nav_items, load_footer_nav())
+      |> assign(:social_links, Site.social_links_for_shop())
+      |> assign(:announcement_text, Site.announcement_text())
+      |> assign(:announcement_link, Site.announcement_link())
+      |> assign(:announcement_style, Site.announcement_style())
 
     {:cont, socket}
   end
@@ -87,10 +91,24 @@ defmodule BerrypodWeb.ThemeHook do
     end
   end
 
-  defp load_nav(key, default) do
-    case Settings.get_setting(key) do
-      items when is_list(items) -> items
-      _ -> default
-    end
+  defp load_header_nav do
+    items = Site.nav_items_for_shop("header")
+    if items == [], do: @default_header_nav, else: add_active_slugs(items)
+  end
+
+  defp load_footer_nav do
+    items = Site.nav_items_for_shop("footer")
+    if items == [], do: @default_footer_nav, else: items
+  end
+
+  # Add active_slugs for Shop nav item to highlight on collection and pdp pages
+  defp add_active_slugs(items) do
+    Enum.map(items, fn item ->
+      if item["slug"] == "collection" do
+        Map.put(item, "active_slugs", ["collection", "pdp"])
+      else
+        item
+      end
+    end)
   end
 end