取消游客模式，强制登录后使用

backend/internal/models/user.go

@@ -13,7 +13,6 @@ const (
 	RoleSystemAdmin RoleName = "system_admin"
 	RoleAdmin       RoleName = "admin"
 	RoleUser        RoleName = "user"
-	RoleGuest       RoleName = "guest"
 )
 
 func (r RoleName) String() string { return string(r) }
@@ -43,10 +42,8 @@ func ParseRoleName(s string) (RoleName, error) {
 		return RoleAdmin, nil
 	case "user":
 		return RoleUser, nil
-	case "guest":
-		return RoleGuest, nil
 	default:
-		return RoleGuest, fmt.Errorf("unknown role: %s", s)
+		return "", fmt.Errorf("unknown role: %s", s)
 	}
 }
 
@@ -105,7 +102,6 @@ func SeedRoles(db *gorm.DB) error {
 		{Name: string(RoleSystemAdmin), Description: strPtr("系统管理员，可管理管理员与系统配置"), Permissions: `["*"]`},
 		{Name: string(RoleAdmin), Description: strPtr("管理员，可管理普通用户"), Permissions: `["users.read", "users.write", "users.create"]`},
 		{Name: string(RoleUser), Description: strPtr("普通用户，可访问业务功能"), Permissions: `["dashboard.read", "profile.write"]`},
-		{Name: string(RoleGuest), Description: strPtr("游客，仅可查看公开内容"), Permissions: `["public.read"]`},
 	}
 	for _, role := range roles {
 		var existing Role