This PR adds support for Hyperliquid's Unified Account mode where Spot USDC
balance can be used as collateral for Perpetual trading.
Changes:
- Add HyperliquidUnifiedAcct field to Exchange config (default: true)
- Update HyperliquidTrader to support unified account mode
- When enabled, Spot USDC balance is added to available trading balance
- Update API request/response structs for unified account toggle
- Update trader config propagation from exchange config
This aligns with Hyperliquid's roadmap to make Unified Account the default.
Gate.io Integration:
- Add Gate trader with full Trader interface implementation
- Add order_sync.go for background trade synchronization
- Fix quantity display (convert contracts to actual tokens via quanto_multiplier)
- Fix fill price return in OpenLong/OpenShort/CloseLong/CloseShort
- Add Gate-specific CoinAnk K-line data source support
- Add Gate to supported exchanges in frontend and backend
- Add Gate/KuCoin logo SVG icons
Trader Package Refactoring:
- Move exchange-specific code into subdirectories (binance/, bybit/, okx/, bitget/, hyperliquid/, aster/, lighter/, gate/)
- Create types/ package for shared types to avoid circular dependencies
- Move TraderTestSuite to trader/testutil package to avoid import cycles
- Update market.GetWithExchange to support exchange-specific data
