feat(psychometric): recover Driver p.16 TRAITVARstd after positive TRAITVAR

[seonghobae]

Stacked on #205 (T0VARstd). Next licensed 2017-era summary.ctsemFit.R std after forming T0VAR/T0VARstd is TRAITVARstd.

Driver, Oud, and Voelkle (2017, Table 2, p. 12 TRAITVAR φ_ξ; §7.1, pp. 18–19; p. 16 suffix std; footnote 4; JSS PDF re-opened 2026-08-23T22:21Z) name traits the stable between-subject differences. The 2017-era source forms TRAITVARstd only when TRAITVAR != 0:

TRAITVARdiag <- diag(diag(TRAITVAR))
TRAITVARstd <- solve(sqrt(TRAITVARdiag)) %&% TRAITVAR

OpenMx %&% is t(A) %*% B %*% A. Unlike T0VARstd, there is no +diag(c(ridging)) addend. Scalar map after strictly positive TRAITVAR is trait / trait = 1.

Recovery

• recover_standardised_trait_variance(trait, clock) forms strictly positive trait, then 1/√trait, then the quadratic.
• Distinct positive trait recover the same 1 (to_bits equal).
• Zero TRAITVAR fails closed (2017-era source skips forming TRAITVARstd).
• Non-event clock fails closed.
• TRAITVAR does not require a < 0.

Claim boundary

• Unstandardised TRAITVAR is not TRAITVARstd (equal numbers when trait = 1 remain distinct named quantities).
• T0VARstd is not TRAITVARstd even when both equal 1.
• addedT0TIPREDVAR t0_b² v is not TRAITVARstd.

Meredith (1993) and Mislevy (1991) remain closed (Unpaywall 2026-08-23T22:21Z: is_oa: false, 0 locations).

Do not merge without an independent APPROVE plus exact-head required-check success. Do not self-approve. Do not request Copilot.

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[seonghobae]

Folded into the consolidation vehicle #231; this draft stays open until the vehicle merges, then closes as superseded-by-consolidation.

[seonghobae]

Superseded by consolidation: this slice's Driver et al. (2017) standardization recovery landed on protected main through the integration vehicles (#231/#232), and its contract coverage is carried by the reconciled suites (multilevel_event_time_recovery_contract, rubin_and_mean_gate_contract) with test-signature repair tracked in #234. The stacked-draft form is retired to keep the delivery queue at review-ready work only; no capability is lost — the exact-head provenance remains in the vehicle PR descriptions and CHANGELOG.