Latest prices across ALL markets (grouped per item)

Baseurl: https://www.steamwebapi.com/markets/prices?key=YOUR_API_KEY

**This is a premium endpoint.**
- Requires Items access in your package (same rate limits as `/steam/api/items`).
- Returns the latest prices across **all configured markets** in one payload.
- Each item appears once with a nested `prices` object keyed by market ident
  (`buff`, `csfloat`, `youpin`, ...). Items missing on a market are omitted from
  that market's slot.

**Parameters:**
- **`key`**: Your API key (required).
- **`market_hash_name`**: Restrict to a single item — strongly recommended for low latency.
- **`markets`**: Comma-separated ident allowlist (e.g. `buff,csfloat`). Default: every active market.
- **`currency`**: Convert prices (optional, default USD).