Minor dev improvements

[PGijsbers]

1. USE_LOCAL_DEV in .env – Currently, USE_LOCAL_DEV is not set, so ./scripts/up.sh starts without applying local changes. We should either set it to true by default or update the documentation to clarify this.
2. sudo commands in ./scripts/clean.sh – Are these necessary? The script works for me without sudo. If it's not required, we could remove them.
3. Minor macOS issue – Port 5000 is already in use on macOS. Using an alternative, like 5001, works fine.

Originally posted by @mrorro in #445 (comment)