feat: add users info to export

[ananastii]

Default info about users in in export file looks like this:
{ "type": "boardMember", "data": { "boardId": "bhowoh6wnh7nqpknm61ckqmi8ye", "userId": "us56ca1pobin1zcajcki5x8supa", "roles": "", "minimumRole": "", "schemeAdmin": true, "schemeEditor": false, "schemeCommenter": false, "schemeViewer": false, "synthetic": false } }

New code extends export file and adds lines with user's info (though I have security concerns about email):

{ "type": "user", "data": { "email": "email@mail.ru", "firstname": "", "lastname": "", "nickname": "", "userId": "123456789abcdefghijklmnopqr", "username": "username" } }

Why do not extend existing boardMember block:

1. Cleaner Separation of Concerns

• BoardMember = permissions/roles
• User = identity information

2. Handles ALL User References
   Users appear as board members, but also in:

• Card creators (createdBy)
• Card modifiers (modifiedBy)
• Card properties (multiPerson fields like "Ответственный")
• Comment authors

3. Backward Compatibility

• Doesn't change the existing boardMember structure