LiveView for creating and editing supplier orders.

Handles:

• :new — creates an empty draft (no supplier, no lines) and

            push_navigate to :edit. Immediate-draft pattern.

• :edit — loads an existing order; :general tab.
• :lines — ordered lines editor (ordered_quantity editable on draft).
• :files — MediaBrowser; storage folder resolved asynchronously.
• :comments — supplier order comments thread.

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.