add owner info

[celogeek]

When we use a vykar server to hold backups of different computer and users, then we can see that the owner of the data is missing.

We already have the Host that can be automatically compute.
Can we also attach the user ?

For example, on the same machine (or different one), I can have 2 accounts, with a workspace directory to backup.
I can play with the label like:

- sources:
   - label: "user1@workspace"
     path: "~/worspace" 

and on the second account:

- sources:
   - label: "user2@workspace"
     path: "~/worspace" 

It could be interesting to have

$ vykar list
ID             Date             Host             User             Label             Source             Files             Size
 f49ea110 2026-05-10 16:51     MyHost             user1             workspace     /Users/user1/workspace.   126,854  5.04 GiB
 f49ea220 2026-05-10 16:51.    MyHost             user2             workspace     /Users/user2/workspace.   126,854  5.04 GiB