consolidate shop pages into unified LiveView for editor state persistence

Replace individual shop LiveViews with a single Shop.Page that dispatches
to page modules based on live_action. This enables patch navigation between
pages, preserving socket state (including editor state) across transitions.

Changes:
- Add Shop.Page unified LiveView with handle_params dispatch
- Extract page logic into Shop.Pages.* modules (Home, Product, Collection, etc.)
- Update router to use Shop.Page with live_action for all shop routes
- Change navigate= to patch= in shop component links
- Add maybe_sync_editing_blocks to reload editor state when page changes
- Track editor_page_slug to detect cross-page navigation while editing
- Fix picture element height when hover image disabled
- Extract ThemeEditor components for shared use

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

lib/berrypod_web/components/shop_components/base.ex

@@ -171,7 +171,7 @@ defmodule BerrypodWeb.ShopComponents.Base do
   def shop_link_button(assigns) do
     ~H"""
     <.link
-      navigate={@href}
+      patch={@href}
       class={["themed-button", @class]}
     >
       {render_slot(@inner_block)}
@@ -203,7 +203,7 @@ defmodule BerrypodWeb.ShopComponents.Base do
   def shop_link_outline(assigns) do
     ~H"""
     <.link
-      navigate={@href}
+      patch={@href}
       class={["themed-button-outline", @class]}
     >
       {render_slot(@inner_block)}