v0.5.1

New features

• coop ssh-config — install a coop-<name> SSH alias (#294) —
  Writes the same ~/.ssh/config block coop vscode produces, but
  without launching an editor, so plain ssh, scp, and rsync reach
  the guest by alias. --clean removes the block. The alias now
  survives coop stop and is refreshed on coop start (the Lima SSH
  port changes per boot), so it stays valid across restarts;
  coop destroy and --clean remove it.

• coop setup --builder-timeout <duration> (#315) — bounds how long
  setup waits for image-build commands before timing out. Accepts bare
  seconds or an s/m/h suffix (e.g. 60m, 2h). Applies across
  both backends.

Removed

• scripts/build-rootfs.sh (#293) — the standalone debootstrap
  rootfs builder is removed. Image creation runs through coop setup,
  which downloads a Firecracker CI squashfs and provisions it with
  scripts/guest/guest-config.sh; the standalone script duplicated that
  provisioning, omitted the CI-kernel workarounds (iptables-legacy,
  static resolv.conf, Docker's DOCKER_INSECURE_NO_IPTABLES_RAW), and
  produced an image the current flow does not consume. The rootfs
  discovery error no longer points at it.