refactor: move person domain components and utils to lib/person/

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

frontend/src/lib/person/person-validation.ts

@@ -0,0 +1,39 @@
+import { m } from '$lib/paraglide/messages.js';
+
+export const PERSON_TYPES = ['PERSON', 'INSTITUTION', 'GROUP', 'UNKNOWN'] as const;
+export type PersonType = (typeof PERSON_TYPES)[number];
+
+export type PersonFormData = {
+	personType?: string | null;
+	title?: string | null;
+	firstName?: string | null;
+	lastName: string;
+	alias?: string | null;
+	birthYear?: number | null;
+	deathYear?: number | null;
+	notes?: string | null;
+};
+
+export function normalizePersonType(raw: string | undefined | null): PersonType {
+	return raw === 'SKIP' ? 'UNKNOWN' : ((raw ?? 'PERSON') as PersonType);
+}
+
+export type PersonValidationKey =
+	| 'validation_last_name_required'
+	| 'validation_first_name_required';
+
+export function resolveValidationMessage(key: PersonValidationKey): string {
+	return key === 'validation_last_name_required'
+		? m.validation_last_name_required()
+		: m.validation_first_name_required();
+}
+
+export function validatePersonFields(
+	personType: string,
+	firstName: string | undefined | null,
+	lastName: string | undefined | null
+): PersonValidationKey | null {
+	if (!lastName) return 'validation_last_name_required';
+	if (personType === 'PERSON' && !firstName) return 'validation_first_name_required';
+	return null;
+}