Operator 2026-06-17. Introduce a minimal, extensible server-level settings.toml
for the cc-ci server; first value SKIP_CANONICALS_FOR_UPGRADE (bool, default
false, false on this server). When true, resolve_upgrade_base bypasses the
canonical and uses the main-tip predecessor — codifying that canonicals are an
optional optimization for the upgrade base. Scoped to the upgrade base only
(promote/--quick separate). Runs after canon/dash (builds on the final resolver).
