WinRacing V64.0 — Controlled Go-Live Rehearsal

Added:
- analysis_chairman_v64_go_live_rehearsal.php
- Chairman/api/api_go_live_rehearsal_v64.php
- Chairman/audit/wr_chairman_go_live_rehearsal_v64_0.php

Purpose:
- Final controlled rehearsal before the production release stage.
- Chains V61 leakage audit, V62 production readiness and V63 shadow certification.
- Locks the source fingerprint and validates deterministic, read-only pre-race operation.
- Provides fail-closed and rollback runbook signals.

Safety:
- No database writes.
- No schema changes.
- No live-weight changes.
- No source-decision mutation.
- Results remain isolated.