LiveView for creating and editing goods issues.

Handles:

• :new — creates an empty draft and push_navigates to :edit.
• :edit — loads an existing issue; :general tab.
• :lines — lines tab: editable issued_quantity with current on-hand shown.

            Draft-only: "Import from internal order" button opens source_picker modal.

• :files — MediaBrowser; storage folder resolved asynchronously.
• :comments — goods issue 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.