LiveView for creating and editing internal orders.

Handles:

• :new — creates a draft and push_navigate to :edit path.
• :edit — loads an existing order; :general tab.
• :items — lines editor (draft only for adding/editing quantities).

Uses the admin header-breadcrumb pattern: use PhoenixKitWeb, :live_view + a self_wrapped_layout on_mount wrapping render/1 in <LayoutWrapper.app_layout> (title in the global admin header). No streams. All navigation paths wrapped in PhoenixKit.Utils.Routes.path/1.