fix(api): emex source-db lookup uses catalogCode+gid, not SSD

Initial design routed emex lookups through vehicles.rawData.ssd → dump vehicles
→ vehicle_parts. Smoke test against prod ssd values: 0 / 10 matched. EMEX
regenerates the SSD on every decode session, so sase's stored SSD never
matches the SSD the dump scraper recorded for the same physical vehicle.

Pivot to a catalog-wide bridge that actually works:
  catalogs.code    ↔ vehicles.rawData.catalogCode  (e.g. "RENAULT201910")
  part_groups.group_id ↔ categories.externalId    (e.g. "11754")
  → parts via vehicle_parts.group_id (dump's parts.group_id is 100% NULL)

Verified coverage on prod's 8287 unique (catalogCode, gid) pairs: 25/26
catalog codes resolve, 7178 pairs hit a part_group (87%), 5919 of those
return actual parts via vehicle_parts (~71% net). Tradeoff: returns all
parts in the (catalog, group) across every variant in the catalog, so the
result is slightly noisier than the live per-vehicle scrape. Acceptable —
parts overlap heavily and the upstream-call savings outweigh the noise.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/src/categories/categories.service.ts

@@ -1092,16 +1092,19 @@ export class CategoriesService {
       } else if (vehicle && category.source === "emex") {
         // EMEX: fetch parts + schema image via Puppeteer from QuickDetails URL
         try {
-          // Local dump first (uses vehicles.rawData.ssd persisted by the
-          // emex mapper). Falls back to live upstream on miss.
-          const emexSsd = (vehicle.rawData as { ssd?: string } | null)?.ssd;
+          // Local dump first (catalog-wide via vehicles.rawData.catalogCode +
+          // category.externalId). The dump's per-vehicle bridge is the EMEX
+          // SSD, which is session-regenerated and never matches what sase
+          // stored — so we accept over-return at the catalog level (~71% hit).
+          // Falls back to live upstream on miss.
+          const catalogCode = (vehicle.rawData as { catalogCode?: string } | null)?.catalogCode;
           let emexResult = await this.emexSourceDb.fetchCategoryParts(
-            emexSsd,
-            category.linkPath ?? "",
+            catalogCode,
+            category.externalId,
           );
           if (emexResult) {
             this.logger.debug(
-              `[source-db hit emex] ssd=${emexSsd?.slice(0, 12)}... gid=${category.externalId}`,
+              `[source-db hit emex] catalog=${catalogCode} gid=${category.externalId}`,
             );
           } else {
             emexResult = await this.emexService.fetchCategoryParts(category.linkPath);