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/components/cards/SourceTypeBadge.tsx

@@ -10,7 +10,6 @@ interface SourceTypeBadgeProps {
 
 const CONFIG: Record<string, { bg: string; color: string; Icon: React.ElementType }> = {
   VERIFIED_PORTFOLIO:  { bg: 'rgba(30,58,95,0.1)',   color: '#1e3a5f', Icon: ShieldCheck },
-  EXTERNAL_MARKET:     { bg: 'rgba(217,119,6,0.1)',  color: '#b45309', Icon: Globe },
   MAISON_WORK:         { bg: 'rgba(3,105,161,0.1)',  color: '#0369a1', Icon: Building2 },
   FUTURE_AVAILABILITY: { bg: 'rgba(124,58,237,0.1)', color: '#6d28d9', Icon: Sparkles },
 }