Human Verification System — additive on TestRun + HumanVerification + FeatureConfidenceRollup

## Context

PDT approved [REDACTED-DOB] (memo: https://www.perplexity.ai/computer/tasks/47e629f8-3cd8-4f1c-9b23-092f0ed8c47b).

Ship the Human Verification System as additive layers over the existing Studio QA fabric (`qa.prisma`) rather than a parallel table family. The `TestCase.featureId` join key + `TestRun.evidence` + `AiTriageLog` already carry every claim a dossier renders; the dossier is a read model, not a write model. The verification writes reuse the `PhiHarmScan` all-set-or-all-null CHECK-constrained verifier trio.

Repo state at approval:
- operant-studio HEAD 1113e5d ([REDACTED-DOB])
- portico HEAD da830ff ([REDACTED-DOB])
- qa.prisma 587 lines, 12 models — no `HumanVerification`, `FeatureDossier`, `experienceScore`, or `smiley` matches
- Precedent: `PhiHarmScan.humanVerdict/By/At` trio at `phi-guard.prisma:41-48`
- Precedent: `CoverageCell` materialized-per-(team,project,feature,kind) at `qa.prisma:139`

## Acceptance Criteria

- 5 children filed and linked to this parent
- Each child scoped so a single agent run can complete it end-to-end (Plan -> Execute -> Review)
- Schema migration child is Stronghold (adds PHI-adjacent `probeText` — Marisol conditional sign-off requires `/// @PHI` + `redactPhi()` + `AuditLog READ_PHI` in the same PR, or the sign-off flips to a veto)
- Renderer, charter generator, rollup materializer, and internal UI children are Safeguard tier
- No user-facing exposure of the smiley beyond internal Studio verifiers until a separate PDT approves Fiesta rollout

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