feat(register-and-statistics): enhance role management logic

- Refactor CreateRole and UpdateRole to handle default roles.
- Add dynamic role assignment using conf settings in 'role.go'.
- Improve request handling with structured data in 'handles/role.go'.
- Implement default role logic in 'db/role.go' for non-default roles.
- Modify 'model/role.go' to include 'Default' field for role management.

internal/op/role.go

@@ -52,6 +52,23 @@ func GetRoleByName(name string) (*model.Role, error) {
 	return r, err
 }
 
+func GetDefaultRoleID() int {
+	item, err := GetSettingItemByKey(conf.DefaultRole)
+	if err == nil && item != nil && item.Value != "" {
+		if id, err := strconv.Atoi(item.Value); err == nil && id != 0 {
+			return id
+		}
+		if r, err := db.GetRoleByName(item.Value); err == nil {
+			return int(r.ID)
+		}
+	}
+	var r model.Role
+	if err := db.GetDb().Where("`default` = ?", true).First(&r).Error; err == nil {
+		return int(r.ID)
+	}
+	return int(model.GUEST)
+}
+
 func GetRolesByUserID(userID uint) ([]model.Role, error) {
 	user, err := GetUserById(userID)
 	if err != nil {

server/handles/auth.go

@@ -109,7 +109,7 @@ func Register(c *gin.Context) {
 	}
 	user := &model.User{
 		Username: req.Username,
-		Role:     model.Roles{setting.GetInt(conf.DefaultRole, int(model.GUEST))},
+		Role:     model.Roles{op.GetDefaultRoleID()},
 		Authn:    "[]",
 	}
 	user.SetPassword(req.Password)

server/handles/user.go

@@ -4,10 +4,8 @@ import (
 	"github.com/alist-org/alist/v3/pkg/utils"
 	"strconv"
 
-	"github.com/alist-org/alist/v3/internal/conf"
 	"github.com/alist-org/alist/v3/internal/model"
 	"github.com/alist-org/alist/v3/internal/op"
-	"github.com/alist-org/alist/v3/internal/setting"
 	"github.com/alist-org/alist/v3/server/common"
 	"github.com/gin-gonic/gin"
 	log "github.com/sirupsen/logrus"
@@ -39,7 +37,7 @@ func CreateUser(c *gin.Context) {
 		return
 	}
 	if len(req.Role) == 0 {
-		req.Role = model.Roles{setting.GetInt(conf.DefaultRole, int(model.GUEST))}
+		req.Role = model.Roles{op.GetDefaultRoleID()}
 	}
 	if req.IsAdmin() || req.IsGuest() {
 		common.ErrorStrResp(c, "admin or guest user can not be created", 400, true)