Price history across ALL markets for one item

Baseurl: https://www.steamwebapi.com/markets/history?key=YOUR_API_KEY&market_hash_name=ITEM

**What this endpoint does:**
- Returns daily price history for a single item across **all configured markets** in one payload.
- Response groups history rows by market ident.

**Parameters:**
- **`key`**: Your API key (required).
- **`market_hash_name`**: The item to get history for (required).
- **`markets`**: Comma-separated market ident allowlist (optional).
- **`start_date`** / **`end_date`**: Date range (YYYY-MM-DD, optional).
- **`currency`**: Convert prices (optional, default USD).

**Important:**
- History is stored daily (1 entry per item per market per day).
- Uses 2 credits per request.