Custom Namespace for App

### Description

In the program, I want the user to be able to create a namespace or choose her own namespace

### Possible solution

Add a new field for namespace name

### Alternatives

_No response_

### Additional information

_No response_

The issue does not identify files, tests, or an entry point for namespace handling. First trace how the application currently selects or creates namespaces, then clarify whether users may create namespaces, choose existing ones, or both, along with the expected completion behavior.

Written by the indexing model from the issue text.