uv syncing and permissions issues

The default set-up suggested here has the `.venv` directory and installed packages owned by the root user, but sets the container user to nonroot. This means that unless you either manually change the permissions of the `.venv` dir, you run the container as root, or you add a flag like `--no-sync` to your uv commands, uv will try to sync up the `.venv` and will trigger a permissions error.

This should either be documented somewhere or the dockerfile altered to suggest running uv without triggering commands that will try alter what's in the `.venv`.

Start by reviewing the repository's Dockerfile and the documented uv commands, then reproduce the setup as the nonroot container user. Trace when uv attempts to sync the root-owned .venv and determine whether the intended resolution is documentation or a Dockerfile change; done means the documented setup no longer produces a permissions error.

Written by the indexing model from the issue text.