feat(vehicles): automatic Vinpin VIN-decode fallback (flag-gated, off by default)

When PL24/pcat/emex can't decode a Fiat VIN, decode it via the Vinpin ePER
web catalog (warm-session Playwright worker, single seat, BullMQ concurrency 1),
cache the exact vehicle in vinpin_decodes, match it to PL24's existing
catalog_vehicle for that model, and serve the parts from there. Vinpin = decode
oracle only; PL24 already holds the parts (e.g. Egea/Linea/Doblo).

Strictly gated behind VINPIN_ENABLED (default false) + a Fiat-only brand
allowlist: with the flag off, decodeVin behaviour is byte-identical and the
queue is never touched (covered by tests). Coordinates/selectors in
vinpin.constants.ts are marked TUNE-AGAINST-LIVE-PAID-SEAT.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/api/drizzle/meta/_journal.json

@@ -148,6 +148,13 @@
       "when": 1781268490495,
       "tag": "0020_stripe_recurring",
       "breakpoints": true
+    },
+    {
+      "idx": 21,
+      "version": "7",
+      "when": 1781568000000,
+      "tag": "0021_vinpin_decodes",
+      "breakpoints": true
     }
   ]
 }