feat(lesereisen): implement lesereisen

frontend/src/lib/person/PersonMultiSelect.svelte

@@ -2,10 +2,11 @@
 import type { components } from '$lib/generated/api';
 import { m } from '$lib/paraglide/messages.js';
 import { clickOutside } from '$lib/shared/actions/clickOutside';
+import type { PersonOption } from './personOption';
 type Person = components['schemas']['Person'];
 
 interface Props {
-	selectedPersons?: Person[];
+	selectedPersons?: PersonOption[];
 }
 
 let { selectedPersons = $bindable([]) }: Props = $props();

frontend/src/lib/person/personFormat.ts

@@ -1,4 +1,5 @@
 import { formatDate } from '$lib/shared/utils/date';
+import { m } from '$lib/paraglide/messages.js';
 
 type Person = { firstName?: string | null; lastName: string; displayName: string };
 type DocForMeta = {
@@ -17,6 +18,19 @@ function djb2(str: string): number {
 	return Math.abs(hash);
 }
 
+/** Localized fallback when a person has no name parts. */
+export function unknownPersonName(): string {
+	return m.person_unknown();
+}
+
+/**
+ * Single source for the join-names-or-fallback rule. Mirrors the server-side
+ * fallback in GeschichteService.toView (which emits the literal '[Unbekannt]').
+ */
+export function joinNameOrUnknown(firstName?: string | null, lastName?: string | null): string {
+	return [firstName, lastName].filter(Boolean).join(' ').trim() || unknownPersonName();
+}
+
 export function getInitials(name: string): string {
 	const words = name.trim().split(/\s+/).filter(Boolean);
 	if (words.length === 0) return '';

frontend/src/lib/person/personOption.ts

@@ -0,0 +1,27 @@
+import type { components } from '$lib/generated/api';
+import { joinNameOrUnknown } from './personFormat';
+
+type Person = components['schemas']['Person'];
+
+/**
+ * Narrow chip/dedup contract for person pickers: exactly what PersonMultiSelect
+ * renders. Full `Person` objects (search results) are structurally assignable;
+ * view projections without a displayName go through {@link toPersonOption}.
+ */
+export type PersonOption = Pick<Person, 'id' | 'displayName'>;
+
+/**
+ * Maps a name-carrying projection (e.g. GeschichteView.PersonView, which has no
+ * server-computed displayName) into the chip contract. Mirrors the server-side
+ * fallback in GeschichteService.toView.
+ */
+export function toPersonOption(p: {
+	id: string;
+	firstName?: string | null;
+	lastName?: string | null;
+}): PersonOption {
+	return {
+		id: p.id,
+		displayName: joinNameOrUnknown(p.firstName, p.lastName)
+	};
+}