feat(eims): derive buyer City/Country from company profile, not global config

City: EimsMapperContext.buyerCity was declared but never wired anywhere —
always null, silently, for every buyer. No dedicated city column on Company;
derives from Zone via a new EIMS_BUYER_CITY_CODES map, same lookup mechanism
as Region/Wereda but optional (an unmapped zone resolves to null rather than
throwing) — MoR has already accepted a live filing with City null.

Country: previously a single flat EIMS_BUYER_COUNTRY_CODE applied to every
buyer regardless of Company.country. Now reads company.country, resolved via
a new EIMS_BUYER_COUNTRY_CODES name-to-code map; the flat env var becomes a
domestic-only fallback (applies only when country is empty/Ethiopia), so an
unmapped foreign buyer fails locally instead of silently filing as Ethiopia.

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

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

@@ -206,8 +206,10 @@ export function buildEimsContext(config: EimsConfig, input: EimsContextInput): E
     incomeWithholdValue: invoice.incomeWithholdValue!,
     transactionWithholdValue: invoice.transactionWithholdValue!,
     buyerCountryCode: invoice.buyerCountryCode,
+    buyerCountryCodes: invoice.buyerCountryCodes,
     buyerRegionCodes: invoice.buyerRegionCodes,
     buyerWeredaCodes: invoice.buyerWeredaCodes,
+    buyerCityCodes: invoice.buyerCityCodes,
     // TEMPORARY — see EimsInvoiceConfig.buyerIdType.
     buyerIdType: invoice.buyerIdType,
     buyerIdNumber: invoice.buyerIdNumber,