feat(frontend): replace all name concatenation with displayName

- Add displayName default method to PersonSummaryDTO
- Update native SQL queries to include title, person_type columns
- Add getInitials() utility to personFormat.ts
- Update abbreviateName/abbreviateCompact for nullable firstName
- Replace firstName+lastName concatenation with displayName in all
  person-displaying components and server load files
- Regenerate API types with displayName on Person and PersonSummaryDTO

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

frontend/src/routes/persons/[id]/NameHistoryCard.svelte

@@ -9,7 +9,7 @@ interface Props {
 		type: string;
 		sortOrder: number;
 	}>;
-	personFirstName: string;
+	personFirstName?: string | null;
 }
 
 let { aliases, personFirstName }: Props = $props();