Amend .cursor/rules/operant-boilerplate.md line 13 to describe Studio's hybrid RLS model

feature_id: FEAT-studio-qa

## Context

Amend `.cursor/rules/operant-boilerplate.md` line 13 to describe Studio's hybrid multi-tenant model: per-team scoping via `withTeamContext(teamId)` (app layer) plus Postgres RLS policies on the 6 sensitive-subset tables (DB layer). The current boilerplate describes only application-layer scoping, which was the drift condition the OPER-104 PDT identified. Ratified: Option C hybrid.

Docs-only. Zero code change. Blocks nothing directly, but is a prereq for OPER-113 landing without contradicting live agent rules.

## Acceptance Criteria

- `.cursor/rules/operant-boilerplate.md` line 13 replaced with the hybrid-model description; both `withTeamContext` and RLS must be named.
- The 6 sensitive tables are enumerated: `Task`, `TaskComment`, `AuditLog`, `PhiReviewPacket`, `Attachment`, `ClassifierClassification`.
- `pnpm check:feature-map` passes locally.
- No other rule files modified in this ticket.