[OPER-PHI-1] Register PHI-eligible reviewer AgentWorker for Studio team

## Context

Three Studio tickets (OPER-113 RLS enable, OPER-QA-6 TestRun state machine, OPER-QA-9 TestRun canvas) are correctly flagged `phiInScope: true` and are stuck at PLANNING_VALIDATED because no PHI-eligible reviewer is registered for the Studio team. The dispatcher's admission gate requires an `AgentWorker` with `kind = "reviewer"`, non-`offline` status, and `"phi"` in `capabilities`.

Per Marisol's PDT constraint ([REDACTED-DOB] PHI-handling memo), every PHI-touching agent-authored PR needs a human-plus-reviewer-agent two-lane review before merge. The reviewer agent is not a second coding agent — it's a lightweight worker that gates on the PHI checklist (no plaintext PHI in test fixtures, `@PHI` annotations present, AuditLog writes, `getOrgScopedDb(orgId)` used, RLS policy tests present).

Portico already has an equivalent reviewer registered (that's why POR-QA-2/3/4 dispatched fine despite touching PHI-adjacent code). This ticket ports the same pattern to the Studio team.

## Goal

An `AgentWorker` row exists on the Studio team with `kind = "reviewer"`, `status = "online"`, and `capabilities` including `"phi"`. Dispatcher's next tick promotes the 3 stuck tickets.

## Human-gate steps

None — this is a data-only registration in the Studio DB. Dispatcher can do it directly via a migration or seed script.

## Agent-owned steps (dispatcher)

1. Read Portico's PHI reviewer AgentWorker row as the reference shape: `SELECT * FROM "AgentWorker" WHERE "teamId" = 'cmrawxwg40004obz9jqc7y5p2' AND kind = 'reviewer' AND 'phi' = ANY(capabilities);`
2. Insert equivalent row for Studio team (teamId `cmrawxvxa0001obz9h9wjtha8`), matching Portico's `runbookRef`, `promptRef`, `slaSeconds`, `capabilities` (must include `phi`), and `status = "online"`.
3. Add a migration `packages/database/prisma/migrations/YYYYMMDD_oper_phi_1_studio_reviewer/` that upserts this row (idempotent). This survives DB rebuilds.
4. Vitest at `packages/dispatcher/src/__tests__/phi-gate.test.ts`: a PHI-flagged ticket on Studio team promotes past the `phi-no-reviewer` gate (integration test against `withTeamContext(studio)`).
5. Confirm OPER-113, OPER-QA-6, OPER-QA-9 flip out of PLANNING_VALIDATED on the next dispatcher tick.

## Acceptance criteria

- `AgentWorker` row exists for Studio team with the required shape (verified by SELECT)
- Migration is committed and idempotent (safe to re-run)
- Vitest phi-gate test passes: registering the reviewer flips a `phiInScope: true` ticket from PLANNING_VALIDATED past the gate
- OPER-113, OPER-QA-6, OPER-QA-9 promote on the next tick (verified by their status changing)

## Why this matters

Unblocks 3 Studio tickets in one shot. Small, mechanical, low-risk. Same pattern already proven in Portico. No PHI is created or exposed by this change — it registers an *identity* that will review future PHI-touching PRs.


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