feat: 算力引擎 Go 后端核心（new-api）

- 统一 OpenAI 兼容 /v1 中继 + 渠道/额度/令牌/流水
- 各领域包：relay 模型网关、model 数据层、controller 管理 API

setting/system_setting/system_setting_old.go

@@ -0,0 +1,10 @@
+package system_setting
+
+var ServerAddress = "http://localhost:3000"
+var WorkerUrl = ""
+var WorkerValidKey = ""
+var WorkerAllowHttpImageRequestEnabled = false
+
+func EnableWorker() bool {
+	return WorkerUrl != ""
+}