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

service/group.go

@@ -0,0 +1,133 @@
+package service
+
+import (
+	"strings"
+
+	"github.com/QuantumNous/new-api/common"
+	"github.com/QuantumNous/new-api/constant"
+	"github.com/QuantumNous/new-api/model"
+	"github.com/QuantumNous/new-api/setting"
+	"github.com/QuantumNous/new-api/setting/ratio_setting"
+	"github.com/gin-gonic/gin"
+)
+
+func GetUserUsableGroups(userGroup string) map[string]string {
+	groupsCopy := setting.GetUserUsableGroupsCopy()
+	if userGroup != "" {
+		specialSettings, b := ratio_setting.GetGroupRatioSetting().GroupSpecialUsableGroup.Get(userGroup)
+		if b {
+			// 处理特殊可用分组
+			for specialGroup, desc := range specialSettings {
+				if strings.HasPrefix(specialGroup, "-:") {
+					// 移除分组
+					groupToRemove := strings.TrimPrefix(specialGroup, "-:")
+					delete(groupsCopy, groupToRemove)
+				} else if strings.HasPrefix(specialGroup, "+:") {
+					// 添加分组
+					groupToAdd := strings.TrimPrefix(specialGroup, "+:")
+					groupsCopy[groupToAdd] = desc
+				} else {
+					// 直接添加分组
+					groupsCopy[specialGroup] = desc
+				}
+			}
+		}
+		// 如果userGroup不在UserUsableGroups中，返回UserUsableGroups + userGroup
+		if _, ok := groupsCopy[userGroup]; !ok {
+			groupsCopy[userGroup] = "用户分组"
+		}
+	}
+	return groupsCopy
+}
+
+func GroupInUserUsableGroups(userGroup, groupName string) bool {
+	_, ok := GetUserUsableGroups(userGroup)[groupName]
+	return ok
+}
+
+func IsUserSelectableGroup(userGroup, groupName string) bool {
+	if groupName == "" || groupName == "auto" {
+		return false
+	}
+	return GroupInUserUsableGroups(userGroup, groupName) && ratio_setting.ContainsGroupRatio(groupName)
+}
+
+// GetUserAutoGroup 根据用户分组获取自动分组设置
+func GetUserAutoGroup(userGroup string) []string {
+	autoGroups := make([]string, 0)
+	seen := make(map[string]struct{})
+	for _, group := range setting.GetAutoGroups() {
+		if !IsUserSelectableGroup(userGroup, group) {
+			continue
+		}
+		if _, ok := seen[group]; ok {
+			continue
+		}
+		seen[group] = struct{}{}
+		autoGroups = append(autoGroups, group)
+	}
+	return autoGroups
+}
+
+// FilterUserTokenAutoGroups applies current permissions before the current
+// per-token limit. It intentionally does not fall back to the global Auto list.
+func FilterUserTokenAutoGroups(userGroup string, groups []string) []string {
+	maxCount := setting.GetMaxTokenAutoGroups()
+	filtered := make([]string, 0, min(len(groups), maxCount))
+	seen := make(map[string]struct{})
+	for _, group := range groups {
+		if !IsUserSelectableGroup(userGroup, group) {
+			continue
+		}
+		if _, ok := seen[group]; ok {
+			continue
+		}
+		seen[group] = struct{}{}
+		filtered = append(filtered, group)
+		if len(filtered) == maxCount {
+			break
+		}
+	}
+	return filtered
+}
+
+// GetRequestAutoGroups resolves the ordered Auto groups for the current token.
+// The absence of the context value means that the token inherits the complete
+// global Auto list; a present (even empty) value is an explicit token snapshot.
+func GetRequestAutoGroups(c *gin.Context, userGroup string) []string {
+	value, ok := common.GetContextKey(c, constant.ContextKeyTokenAutoGroups)
+	if !ok {
+		return GetUserAutoGroup(userGroup)
+	}
+	groups, ok := value.([]string)
+	if !ok {
+		return []string{}
+	}
+	return FilterUserTokenAutoGroups(userGroup, groups)
+}
+
+// GetGroupsEnabledModels 按 groups 顺序获取各分组启用的模型并去重
+func GetGroupsEnabledModels(groups []string) []string {
+	seen := make(map[string]struct{})
+	models := make([]string, 0)
+	for _, group := range groups {
+		for _, modelName := range model.GetGroupEnabledModels(group) {
+			if _, ok := seen[modelName]; !ok {
+				seen[modelName] = struct{}{}
+				models = append(models, modelName)
+			}
+		}
+	}
+	return models
+}
+
+// GetUserGroupRatio 获取用户使用某个分组的倍率
+// userGroup 用户分组
+// group 需要获取倍率的分组
+func GetUserGroupRatio(userGroup, group string) float64 {
+	ratio, ok := ratio_setting.GetGroupGroupRatio(userGroup, group)
+	if ok {
+		return ratio
+	}
+	return ratio_setting.GetGroupRatio(group)
+}