v41: volume-selectable CPU create + idempotent fetch

v41 launcher: selectable network volume

v41: same-DC pre-fetch worker + authenticated runner fetch

v41 launcher: shell runner that bootstraps python3/curl

v41 launcher: --no-network-volume

v41: gpu workers

v41: publish worker + fixed packer bundle

v41 quant: headless CPU worker + runtime tree + V4.1 packer