Warehouse-location settings page (/admin/settings/warehouse).
Extracted from the warehouse section of Andi's /admin/settings/andi
page (lib/andi_web/live/admin/settings/andi.ex) — which location type
marks warehouses and which location is the default warehouse for stock.
Both persist to PhoenixKit.Settings (admin-configurable, no redeploy)
via PhoenixKitWarehouse.StockLedger.
Admin-chrome pattern: use PhoenixKitWeb, :live_view + <.admin_page_header>.