Decouple client.py from server build

[shreddd]

Currently the client package is bundled with the server dependencies. We should consider making the client a dev tool, so that it doesn't get included in the server build for the pypi package.

Potential cleanup:

• Drop requirements.txt (since these should be captured in pyproject.toml
• Use dev section in pyproject.toml to make sure client.py requirements are not pulled into server
• Optionally split off client into standalone separate directory to avoid confusion.