I will give my 2 cents.
I would create a new table in a database consisting of the following columns with some sample data:
id | project_id | parent_id | name
1 | 1 | null | Main Folder
2 | 1 | 1 | Child Folder
3 | 1 | 2 | Child of Child Folder
4 | 2 | null | Main Folder Hehe
5 | 2 | 4 | Child Folder Hehe
node, , .
, parent_id null, , , , .
, /!
- .