feat(eims): seller identity enriched from e-Trade, cached (bootstrap only)

Ten EIMS_SELLER_* env vars were the only source of EDR's own seller identity,
duplicating data the platform already has via the same e-Trade lookup used
for every customer company at onboarding. EimsSellerCacheService now enriches
it — but static config remains the source of truth: MoR validates
SellerDetails against its own taxpayer registry (rule 7017, already cleared
against the current static values), so e-Trade fills a field only when the
static value is blank, never overrides one already confirmed. The static
config is therefore the durable fallback, not the cache; an in-memory
snapshot lost on restart is harmless.

ETradeService has no request timeout of its own and no AbortController, so
the cache enforces one locally (stops waiting, doesn't cancel the request)
and de-duplicates concurrent refresh() calls into the same in-flight promise.
getSellerDetails() is fully synchronous — zero I/O — so live registration
never depends on e-Trade being reachable, at boot or per invoice.

VatNumber and Email stay on static config permanently — confirmed by reading
e-Trade's actual response shapes, neither field exists anywhere in what it
returns. Region/Wereda/City reuse the existing EIMS_BUYER_*_CODES maps rather
than adding seller-specific ones — the geography is objective, not
buyer-specific.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/edr-freight-api/src/modules/billing/eims-invoice.mapper.ts

@@ -371,6 +371,25 @@ function resolveCountryCode(
   );
 }
 
+/**
+ * Same name-or-code resolution as `resolveLocationCode`, for a caller with no invoice to attach an
+ * error to and that must never throw — currently only `EimsSellerCacheService`, resolving
+ * e-Trade's region/zone/woreda *names* for EDR's own seller identity. Pass-through numeric code,
+ * name lookup, `undefined` on no match — the caller falls back to static config either way.
+ */
+export function resolveOptionalCode(
+  value: string | null | undefined,
+  codes: Record<string, string>,
+): string | undefined {
+  const raw = (value ?? "").trim();
+  if (LOCATION_CODE.test(raw)) return raw;
+  const key = raw.toLowerCase().replace(/\s+/g, " ");
+  const mapped = Object.entries(codes).find(
+    ([name]) => name.trim().toLowerCase().replace(/\s+/g, " ") === key,
+  )?.[1];
+  return mapped && LOCATION_CODE.test(mapped) ? mapped : undefined;
+}
+
 export function toEimsInvoice(
   invoice: EimsMapperInvoice,
   seller: EimsSellerDetails,