v0.1.2

feat: credential-free work extraction — fetch-url and export

- fetch-url <name>: prints a git fetch line that pulls a branch out of
  the instance over docker exec stdio (ext transport); no credentials
  ever enter the container — the host reviews, then pushes itself
- export <name> <dir>: copy /workspace to a host directory (inverse of
  --seed, reads the volume directly so it works while stopped); refuses
  a non-empty destination