Cover warehouse management (create, list, primary), inventory operations
(add/remove stock, reserve/release/fulfil), stock transfers between
warehouses, stock count adjustments, query methods (total stock, available
stock, low/out of stock, movement history, best warehouse), and full
order lifecycle integration tests.
Fixes#8
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
