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/lib/utils/personFormat.ts

@@ -1,6 +1,6 @@
 import { formatDocumentStatus } from './documentStatusLabel';
 
-type Person = { firstName: string; lastName: string };
+type Person = { firstName?: string | null; lastName: string; displayName: string };
 type DocumentStatus = 'PLACEHOLDER' | 'UPLOADED' | 'TRANSCRIBED' | 'REVIEWED' | 'ARCHIVED';
 type DocForMeta = {
 	sender?: Person | null;
@@ -18,7 +18,13 @@ function djb2(str: string): number {
 	return Math.abs(hash);
 }
 
+export function getInitials(person: Person): string {
+	if (person.firstName) return `${person.firstName[0]}${person.lastName[0]}`.toUpperCase();
+	return person.lastName.substring(0, 2).toUpperCase();
+}
+
 export function abbreviateName(person: Person): string {
+	if (!person.firstName) return person.lastName;
 	const first = person.firstName.trim();
 	const last = person.lastName.trim();
 	if (!last) return first;
@@ -26,6 +32,7 @@ export function abbreviateName(person: Person): string {
 }
 
 function abbreviateCompact(person: Person): string {
+	if (!person.firstName) return person.lastName;
 	const first = person.firstName.trim();
 	const last = person.lastName.trim();
 	if (!last) return first;