Era-binding verify invariants all SKIP on a report that DID narrow eras via a ci.yml change

Migrated from the pre-public development archive (issue #131 there); archive PR/issue numbers in the body refer to that archive.

Pre-flip audit (live run on unicity-aos/aos-ce, ~9-day-old repo), LOW, not gating.

The rendered report carried a config-era narrowing banner ("ci.yml changed ~12 hours ago ... measures only the 7 runs since ... 13 earlier runs excluded"), yet all six era-binding invariants in verify_report SKIPped with "no workflow sample straddled a config change — no era to bind". The guards appear to key on a per-pole magnitude straddle, not the workflow-level narrowing that drove the banner, so the exact report that narrowed eras is not validated by the era-honesty gate.

Coverage gap in the honesty gate, not a user-visible defect. Worth binding the invariants to whatever emitted the narrowing banner.