Trigger the 6 international physical-gold scrapers (per-source isolation)

Fans out to bnm_my, vangtoday, sge_cn, sarafa_pk, forexpk, dubaicityofgold — one route per wave, concurrently via _run_physical_dispatch, same per-source isolation shape as /physical-gold-id (Indonesia).

Cadence: 15 minutes (see 20260703120300_physical_gold_intl_pg_cron.sql). Dead-man 2x per source = 30 min.

Dark launch: this route has no tier/pricing gating — it exists purely to populate raw_physical_gold ahead of the TIERS_V2 flip (§6b PR-3), same posture as /physical-gold-id.