ui(fairness): publish re-evaluation and review-parity series

[JSONbored]

Problem

Once computed (sibling sub-issue), both series need a public surface with enough context to be read correctly.

Scope

• /fairness additions: re-evaluation rate (with reason-code breakdown) and the author-class parity table, each with a short methodology note and the basis/coverage annotations used by existing fairness numbers
• Zero-value states handled honestly (post-Reversal signal is unavailable on the hosted runtime, so own-ledger accuracy is unmeasurable there #9676 conventions): "no re-evaluations recorded" is shown as measured-zero with its window, not as a blank
• Linked from the verify-this-review walkthrough

Acceptance

Both series visible and self-explanatory on /fairness; the public verifier confirms page values match the stats endpoint.

[linear-code]

JSO-6805