when a todo is marked as "done"
a new line is added with the "done date"

## Done: 2026-01-09

when you do a todo list it then order & group based on the done date :

./nb todos
TODO :
[3] ✔️  [ ] documentation
2026-01-09 :
[2] ✅ [x] roadmap
Done without date :
[1] ✅ [x] meeting