A runner key claims builds only for the repositories it is attached to
(repo runner add|list|remove, also on the settings page). runner next
skips untrusted builds unless --untrusted; runner log and runner done
refuse a build outside the key's attachments; the bypass is a full-scope
admin key, not the account. Migration 0050 adds runner_repos and rekeys
runner_seen by key. gitbay-runner init, config.toml, -identity,
-untrusted. Wiki: Users, Admin, Threat-Model, Parity, FAQ, CI.
After deploy, attach the bay1 runner to krz/gitbay and cmc/ci-smoke as
the admin; until then it claims nothing. The bay1 unit gains -untrusted.
Ref #184