Youpin Doppler bid (buy order) prices

Youpin bid (buy order) prices and bid_volume now cover all Doppler and Gamma Doppler items. ask_volume is also now available. Refresh rate on all Youpin Doppler data (bid & ask) is now ~5 minutes on most items (with very illiquid knives @ ~20 minutes).

This data is available on GET /v1/prices/latest with bid history from July 26th, 2026 onwards on POST /v1/prices/history.