Operator 2026-06-17: (1) no-canonical upgrade base should prefer the most recent
release TAG < head (a real published predecessor, reusing samever's helper),
with raw main-tip only as a last resort, then skip — always-on, improves this
server too. (2) SKIP_CANONICALS_FOR_UPGRADE=true feeds that same release-tag-first
fallback (so it swaps canonical->latest-release base without losing upgrade
coverage). (3) model bumped sonnet->opus.
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).
