Do not install dependencies as those are no longer maintained.
Instead use the shell to set path to local installed version and miss
use nix-shell to build an environment that works for me for now.
Remove flakes for now.
I will use shells for now to not have a mixed setup.
Add composer v1 for a single customer project as overlay due to usage in
shell instead of flakes.
Adjust folder to not have unnecessary deep structure.
Add shell for reuter monorepo using composer v1.