feat: 支持Anthropic API协议 | support Anthropic API protocol

- 添加Anthropic适配器实现 | Add Anthropic adaptor implementation
- 支持Anthropic消息格式转换 | Support Anthropic message format conversion
- 添加Vertex AI Claude适配器支持 | Add Vertex AI Claude adapter support
- 更新Anthropic的中继模式定义 | Update relay mode definitions for Anthropic
- 添加Anthropic控制器和路由 | Add Anthropic controller and routing

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

Co-Authored-By: zgdmemail@gmail.com

controller/relay.go

@@ -36,6 +36,8 @@ func relayHelper(c *gin.Context, relayMode int) *model.ErrorWithStatusCode {
 		err = controller.RelayAudioHelper(c, relayMode)
 	case relaymode.Proxy:
 		err = controller.RelayProxyHelper(c, relayMode)
+	case relaymode.AnthropicMessages:
+		err = controller.RelayAnthropicHelper(c)
 	default:
 		err = controller.RelayTextHelper(c)
 	}