Make `banger vm list` easier to scan by resolving each VM image ID back to the registered image name when that mapping is available, while still falling back to a short ID for unknown images.
Raise the shared default VM memory from 1024 MiB to 2048 MiB so new VMs, CLI help, and daemon-side defaults all align on a 2 GiB baseline.
Add CLI coverage for the image-name rendering path and validate the change with go test ./..., make build, `banger vm list`, and `banger vm create --help`.