Use when working with stock in Spree 6 — StockLevel counters (count_on_hand, allocated_count, reserved_count, incoming_count, available/purchasable), stock locations (kind, pickup_enabled, returns_enabled), stock movements and their kinds, checkout stock reservations and their expiry job, backorders, inventory tracking on/off, bulk stock sync from an ERP/WMS (bulk_upsert), stock transfers, suppliers, purchase orders and stock receipts, the spree:stock:recount_levels task, and stock_level events.
