Kickoff box name: measured hostname, or a friendly studio name? nf-5na ← Beads

Twinned from https://github.com/cfsh/ninefold/issues/607 by tools/beads/import_github.py's reconcile pass.

#603 makes spawn_dev.py measure the box instead of hardcoding it, so a generated kickoff now opens with what it measured: `on nf-dev-sg (Linux)`. That is what a machine can read off itself. It is not the name you use for these boxes in conversation ("the office box", "the garage VM").

• A — measured hostname + OS (ships today): `on nf-dev-sg (Linux)`. Cannot go stale, cannot be wrong, and omits itself entirely when nothing resolves. Costs the reader one translation from hostname to the box they picture.
• B — friendly name: a hostname→role table so the kickoff reads "on the garage VM". Reads better on the first line a session ever sees; it is also a literal about studio state, which is exactly what #601 cost. If B, the table belongs in the office repo (studio state), not in spawn_dev.py.

Recommended default: A. #603 ships it, and the PR asks this same question in its own body — this issue exists so it is answerable from the issue list rather than out of PR prose.

Default ships if unanswered — nothing is blocked on this.