research spike: workspace name

[pmeier]

The workspace name is currently tightly coupled to the pixi.toml manifest. This prevents us from having multiple workspaces with the same name from different sources, e.g. server and OCI registry. The pixi.toml does not require the name to be in there:

The name of the workspace. If the name is not specified, the name of the directory that contains the workspace is used.

The questions this research spike should answer:

1. Can we detach the workspace name from the pixi.toml manifest?
2. If yes, how large is the effort? For this BC of the database is not a concern as long as a script etc. can be run against an old DB to upgrade to the new schema.