feat: remove EXTERNAL_MARKET result type entirely

All external market properties now surface as VERIFIED_PORTFOLIO.
Removes the type from enums, domain types, mock data, matching engine,
components, hooks, and tests — zero user-visible distinction remains.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/supply/newListingMapper.ts

@@ -47,7 +47,7 @@ export function buildCreatePropertyInput(fields: {
   return {
     title: `${ASSET_TYPE_LABELS[assetType] ?? assetType} · ${city}`,
     assetType: assetType as typeof AssetType[keyof typeof AssetType],
-    resultType: ResultType.EXTERNAL_MARKET,
+    resultType: ResultType.VERIFIED_PORTFOLIO,
     sourceType: 'DIRECT',
     location: { city, country: 'CH' },
     address: {