A logistics company stores shipment events in a Cosmos DB container. Each event has a warehouseId (only 8 distinct values, causing hot partitions) and a timestamp. Most queries filter by warehouseId AND a date range (e.g., all events for a warehouse in a given month). The team wants to spread writes more evenly while still allowing efficient date-range queries scoped to a single partition. Which partition key design best meets these needs?