feat(gate): complete Gate.io exchange integration with trader refactoring

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

go.mod

@@ -23,6 +23,7 @@ require (
 
 require (
 	github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251001021608-1fe7b43fc4d6 // indirect
+	github.com/antihax/optional v1.0.0 // indirect
 	github.com/armon/go-radix v1.0.0 // indirect
 	github.com/bitly/go-simplejson v0.5.1 // indirect
 	github.com/bits-and-blooms/bitset v1.24.0 // indirect
@@ -44,6 +45,7 @@ require (
 	github.com/ethereum/c-kzg-4844/v2 v2.1.5 // indirect
 	github.com/ethereum/go-verkle v0.2.2 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
+	github.com/gateio/gateapi-go/v6 v6.104.3 // indirect
 	github.com/gin-contrib/sse v1.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect