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/domain/enums.ts

@@ -14,7 +14,6 @@ export type AssetType = typeof AssetType[keyof typeof AssetType]
 // ── Result Types ──────────────────────────────────────────────────────────────
 export const ResultType = {
   VERIFIED_PORTFOLIO: 'VERIFIED_PORTFOLIO',
-  EXTERNAL_MARKET: 'EXTERNAL_MARKET',
   MAISON_WORK: 'MAISON_WORK',
   FUTURE_AVAILABILITY: 'FUTURE_AVAILABILITY',
 } as const