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/+page.svelte

@@ -99,13 +99,12 @@ function handleSearch() {
 						<div
 							class="flex h-12 w-12 flex-shrink-0 items-center justify-center rounded-full bg-primary font-serif text-base font-bold text-primary-fg transition-colors"
 						>
-							{person.firstName?.[0]}{person.lastName?.[0]}
+							{person.firstName ? person.firstName[0] : person.lastName[0]}{person.lastName[0]}
 						</div>
 
 						<!-- Name -->
 						<p class="font-serif text-sm font-bold text-ink group-hover:underline">
-							{person.firstName}
-							{person.lastName}
+							{person.displayName}
 						</p>
 
 						<!-- Alias -->