Feature: Add support for custom OpenAI-compatible API

This update enables users to configure any OpenAI-compatible API endpoint,
allowing the use of:
- OpenAI official API (GPT-4, GPT-4o, etc.)
- OpenRouter (access to multiple models)
- Local deployed models (Ollama, LM Studio, etc.)
- Other OpenAI-format compatible API services

Changes:
- config: Add custom_api_url, custom_api_key, custom_model_name fields
- mcp: Add SetCustomAPI function and ProviderCustom constant
- trader: Update AI initialization logic to support custom API
- manager: Pass custom API config to trader instances
- Add CUSTOM_API.md documentation with usage examples
- Update config.json.example with custom API sample

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

manager/trader_manager.go

@@ -45,6 +45,9 @@ func (tm *TraderManager) AddTrader(cfg config.TraderConfig, coinPoolURL string,
 		UseQwen:               cfg.AIModel == "qwen",
 		DeepSeekKey:           cfg.DeepSeekKey,
 		QwenKey:               cfg.QwenKey,
+		CustomAPIURL:          cfg.CustomAPIURL,
+		CustomAPIKey:          cfg.CustomAPIKey,
+		CustomModelName:       cfg.CustomModelName,
 		ScanInterval:          cfg.GetScanInterval(),
 		InitialBalance:        cfg.InitialBalance,
 		BTCETHLeverage:        leverage.BTCETHLeverage,  // 使用配置的杠杆倍数