Trigger the 3 wave-4 physical-gold scrapers (per-source isolation)

Fans out to ibja_in (India), goldpricedata_sa (Saudi Arabia), hkgoldrate_hk (Hong Kong) — one route per wave, concurrently via _run_physical_dispatch, same per-source isolation shape as the earlier physical routes.

Cadence: 15 minutes (see 20260706120000_physical_gold_w4_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 the earlier physical waves.