fix: add delay after cancelAllOrders to wait for WS events
Problem: cancelAllOrders() returns immediately after sending the
cancel request, but order cancellation events arrive via WebSocket
asynchronously. This causes new orders to be created before the
cancellation events are processed, leading to order accumulation.
Solution: Add 1 second delay after cancelAllOrders() to allow
WebSocket order cancellation events to propagate and be processed
before creating new orders.
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Co-Authored-By: Claude <noreply@anthropic.com>