HV-3: Charter generator -- packages/qa/src/charter.ts + nightly quality eval

---
feature_id: FEAT-studio-qa
size: M
module: qa
phi_in_scope: true
has_migration: false
write_sets:
  - packages/qa/src/charter.ts
  - packages/qa/src/charter-eval.ts
  - apps/web/src/app/api/cron/charter-quality/route.ts
---

## Context

Parent: OPER-196.

AI-authored Human Verification Charter generated from the dossier (HV-2) + `TestCase.tags[]` feature-type. Uses the same triage classifier plumbing OPER-177 already ships (`packages/qa/src/ai-triage.ts`). Charter output logs to `AiTriageLog` with `kind = CHARTER` (extend `AiTriageLogKind` enum).

Shankar dissent from the PDT memo requires shipping `charterQualityScore` in the same ticket: a nightly cron that reads each new charter's claims and checks whether they are grounded in the referenced code diff. Ungrounded claims decrement the score.

## Acceptance Criteria

- `generateCharter({ dossier, featureType }): Promise<Charter>` in `packages/qa/src/charter.ts`
- Extend `AiTriageLogKind` enum with `CHARTER` value in `qa.prisma` (additive migration)
- Cron route `/api/cron/charter-quality` runs nightly, scores each new charter, writes `charterQualityScore` back to the `AiTriageLog` row
- Feature-type vocabulary lives in `packages/qa/src/feature-types.ts` as a validated string set (`clinical-workflow`, `data-entry`, `report`, `automation`, `phi-sensitive`, `family-facing`, `money`, `bulk`)
- Vitest tests cover charter generation for each of the eight feature types

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**Planner rescope (phi_no_reviewer):** Task has phiInScope=true but no PHI-eligible reviewer is available. Register a reviewer worker advertising the `phi` capability before admitting PHI work.