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/auto_group.go

@@ -0,0 +1,70 @@
+package setting
+
+import (
+	"fmt"
+	"strconv"
+	"sync/atomic"
+
+	"github.com/QuantumNous/new-api/common"
+)
+
+const DefaultMaxTokenAutoGroups = 5
+
+var autoGroups = []string{
+	"default",
+}
+
+var DefaultUseAutoGroup = false
+
+var maxTokenAutoGroups atomic.Int64
+
+func init() {
+	maxTokenAutoGroups.Store(DefaultMaxTokenAutoGroups)
+}
+
+func ContainsAutoGroup(group string) bool {
+	for _, autoGroup := range autoGroups {
+		if autoGroup == group {
+			return true
+		}
+	}
+	return false
+}
+
+func UpdateAutoGroupsByJsonString(jsonString string) error {
+	autoGroups = make([]string, 0)
+	return common.Unmarshal([]byte(jsonString), &autoGroups)
+}
+
+func AutoGroups2JsonString() string {
+	jsonBytes, err := common.Marshal(autoGroups)
+	if err != nil {
+		return "[]"
+	}
+	return string(jsonBytes)
+}
+
+func GetAutoGroups() []string {
+	return autoGroups
+}
+
+func GetMaxTokenAutoGroups() int {
+	return int(maxTokenAutoGroups.Load())
+}
+
+func ValidateMaxTokenAutoGroups(value string) error {
+	maxCount, err := strconv.Atoi(value)
+	if err != nil || maxCount <= 0 {
+		return fmt.Errorf("MaxTokenAutoGroups must be a positive integer")
+	}
+	return nil
+}
+
+func UpdateMaxTokenAutoGroups(value string) error {
+	if err := ValidateMaxTokenAutoGroups(value); err != nil {
+		return err
+	}
+	maxCount, _ := strconv.Atoi(value)
+	maxTokenAutoGroups.Store(int64(maxCount))
+	return nil
+}