feat(persons): add type selector + title + conditional fields to new-person form

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

frontend/src/routes/persons/new/+page.server.ts

@@ -1,5 +1,6 @@
 import { error, fail, redirect } from '@sveltejs/kit';
 import { createApiClient } from '$lib/api.server';
+import { getErrorMessage } from '$lib/errors';
 
 export async function load({ locals }: { locals: App.Locals }) {
 	const canWrite =
@@ -12,6 +13,12 @@ export async function load({ locals }: { locals: App.Locals }) {
 export const actions = {
 	default: async ({ request, fetch }) => {
 		const formData = await request.formData();
+		const personType = (formData.get('personType')?.toString() ?? 'PERSON') as
+			| 'PERSON'
+			| 'INSTITUTION'
+			| 'GROUP'
+			| 'UNKNOWN';
+		const title = formData.get('title')?.toString().trim() || undefined;
 		const firstName = formData.get('firstName')?.toString().trim();
 		const lastName = formData.get('lastName')?.toString().trim();
 		const alias = formData.get('alias')?.toString().trim() || undefined;
@@ -19,8 +26,25 @@ export const actions = {
 		const deathYearStr = formData.get('deathYear')?.toString().trim();
 		const notes = formData.get('notes')?.toString().trim() || undefined;
 
-		if (!firstName || !lastName) {
-			return fail(400, { error: 'Vor- und Nachname sind Pflichtfelder.' });
+		if (!lastName) {
+			return fail(400, {
+				error: 'Nachname ist Pflichtfeld.',
+				personType,
+				title,
+				firstName,
+				lastName: '',
+				alias
+			});
+		}
+		if (personType === 'PERSON' && !firstName) {
+			return fail(400, {
+				error: 'Vorname ist Pflichtfeld.',
+				personType,
+				title,
+				firstName: '',
+				lastName,
+				alias
+			});
 		}
 
 		const birthYear = birthYearStr ? parseInt(birthYearStr, 10) : undefined;
@@ -29,8 +53,10 @@ export const actions = {
 		const api = createApiClient(fetch);
 		const result = await api.POST('/api/persons', {
 			body: {
-				firstName,
-				lastName,
+				personType,
+				...(title ? { title } : {}),
+				...(firstName ? { firstName } : {}),
+				lastName: lastName!,
 				...(alias ? { alias } : {}),
 				...(birthYear ? { birthYear } : {}),
 				...(deathYear ? { deathYear } : {}),
@@ -39,7 +65,15 @@ export const actions = {
 		});
 
 		if (!result.response.ok) {
-			return fail(result.response.status, { error: 'Person konnte nicht gespeichert werden.' });
+			const code = (result.error as unknown as { code?: string })?.code;
+			return fail(result.response.status, {
+				error: getErrorMessage(code),
+				personType,
+				title,
+				firstName,
+				lastName: lastName!,
+				alias
+			});
 		}
 
 		throw redirect(303, `/persons/${result.data!.id}`);