feat(trader): add Indodax exchange integration (#1400)

* feat(trader): add Indodax exchange integration

- Add IndodaxTrader implementing types.Trader interface for spot trading
- Support HMAC-SHA512 authentication with Key/Sign headers
- Map spot buy/sell to OpenLong/CloseLong, stub futures-only methods
- Wire up auto_trader.go, trader_manager.go, store/exchange.go
- Add Indodax to frontend ExchangeConfigModal and ExchangeIcons
- Add integration tests with env-var based credentials
- Add Indodax logo assets (PNG + SVG)

* fix: type validation at server.go for indodax exchange

manager/trader_manager.go

@@ -407,7 +407,6 @@ func (tm *TraderManager) GetTopTradersData() (map[string]interface{}, error) {
 	return result, nil
 }
 
-
 // RemoveTrader removes a trader from memory (does not affect database)
 // Used to force reload when updating trader configuration
 // If the trader is running, it will be stopped first
@@ -664,11 +663,11 @@ func (tm *TraderManager) addTraderFromStore(traderCfg *store.Trader, aiModelCfg
 		QwenKey:               "",
 		CustomAPIURL:          aiModelCfg.CustomAPIURL,
 		CustomModelName:       aiModelCfg.CustomModelName,
-		ScanInterval:         time.Duration(traderCfg.ScanIntervalMinutes) * time.Minute,
-		InitialBalance:       traderCfg.InitialBalance,
-		IsCrossMargin:        traderCfg.IsCrossMargin,
-		ShowInCompetition:    traderCfg.ShowInCompetition,
-		StrategyConfig:       strategyConfig,
+		ScanInterval:          time.Duration(traderCfg.ScanIntervalMinutes) * time.Minute,
+		InitialBalance:        traderCfg.InitialBalance,
+		IsCrossMargin:         traderCfg.IsCrossMargin,
+		ShowInCompetition:     traderCfg.ShowInCompetition,
+		StrategyConfig:        strategyConfig,
 	}
 
 	logger.Infof("📊 Loading trader %s: ScanIntervalMinutes=%d (from DB), ScanInterval=%v",
@@ -711,6 +710,9 @@ func (tm *TraderManager) addTraderFromStore(traderCfg *store.Trader, aiModelCfg
 		traderConfig.LighterAPIKeyPrivateKey = string(exchangeCfg.LighterAPIKeyPrivateKey)
 		traderConfig.LighterAPIKeyIndex = exchangeCfg.LighterAPIKeyIndex
 		traderConfig.LighterTestnet = exchangeCfg.Testnet
+	case "indodax":
+		traderConfig.IndodaxAPIKey = string(exchangeCfg.APIKey)
+		traderConfig.IndodaxSecretKey = string(exchangeCfg.SecretKey)
 	}
 
 	// Set API keys based on AI model (convert EncryptedString to string)