Fix Operant-team dispatcher PAT scope (403 on branch create)

## Problem

After OPER-11A shipped, Operant-team tasks fail branch creation with HTTP 403 and get parked AWAITING_HUMAN. Zero Operant tasks can dispatch until PAT scope is fixed.

## Evidence

12 rows in DispatchAudit at 2026-07-16T02:53Z, all outcome=`branch_create_failed_non_retriable`, httpStatus=403, spanning OPER-8A/9A/9/10/11/12/13/14. Branches like `justin/oper-11-...` and `operant-cron/OPER-9a-...`.

## Suspected cause

The org-wide PAT (vault UUID `04103fb0-c433-49ce-a395-00a9f1f179e0`, identity `operant-justin-blanchard`) has contents:write on Portico but not on the repo Operant-team dispatches target. Verify which repo Operant tasks resolve to and grant contents:write.

## Acceptance

- New Operant dispatch attempt returns 201 (or 422 already-exists), not 403
- DispatchAudit rows show outcome=`branch_created` for Operant team
- The 8 currently-parked Operant tasks can be un-parked (status back to PLANNING_VALIDATED) and successfully dispatch

## Related

- OPER-11A (shipped, this is downstream)
- Blocks: any auto-shipping from Operant team