feat: add create person feature via web interface

- Backend: new POST /api/persons endpoint in PersonController
- Frontend: new /persons/new route with Vorname/Nachname/Alias form,
  redirects to the new person's detail page on success
- Persons list: subtle '+ Neue Person' link below the page title

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

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

@@ -0,0 +1,26 @@
+import { fail, redirect } from '@sveltejs/kit';
+import { createApiClient } from '$lib/api.server';
+
+export const actions = {
+	default: async ({ request, fetch }) => {
+		const formData = await request.formData();
+		const firstName = formData.get('firstName')?.toString().trim();
+		const lastName = formData.get('lastName')?.toString().trim();
+		const alias = formData.get('alias')?.toString().trim() || undefined;
+
+		if (!firstName || !lastName) {
+			return fail(400, { error: 'Vor- und Nachname sind Pflichtfelder.' });
+		}
+
+		const api = createApiClient(fetch);
+		const result = await api.POST('/api/persons', {
+			body: { firstName, lastName, ...(alias ? { alias } : {}) }
+		});
+
+		if (!result.response.ok) {
+			return fail(result.response.status, { error: 'Person konnte nicht gespeichert werden.' });
+		}
+
+		throw redirect(303, `/persons/${result.data!.id}`);
+	}
+};

frontend/src/routes/persons/new/+page.svelte

@@ -0,0 +1,100 @@
+<script lang="ts">
+export let form;
+</script>
+
+<div class="mx-auto max-w-2xl px-4 py-8">
+	<!-- Heading -->
+	<div class="mb-6">
+		<a
+			href="/persons"
+			class="group mb-4 inline-flex items-center text-xs font-bold tracking-widest text-gray-500 uppercase transition-colors hover:text-brand-navy"
+		>
+			<svg
+				class="mr-2 h-4 w-4 transform transition-transform group-hover:-translate-x-1"
+				fill="none"
+				stroke="currentColor"
+				viewBox="0 0 24 24"
+			>
+				<path
+					stroke-linecap="round"
+					stroke-linejoin="round"
+					stroke-width="2"
+					d="M10 19l-7-7m0 0l7-7m-7 7h18"
+				/>
+			</svg>
+			Zurück zur Übersicht
+		</a>
+		<h1 class="font-serif text-3xl text-brand-navy">Neue Person</h1>
+	</div>
+
+	{#if form?.error}
+		<div class="mb-6 rounded border border-red-200 bg-red-50 p-4 text-red-700">{form.error}</div>
+	{/if}
+
+	<form method="POST" class="pb-20">
+		<div class="rounded-sm border border-brand-sand bg-white p-6 shadow-sm">
+			<h2 class="mb-5 text-xs font-bold tracking-widest text-gray-400 uppercase">
+				Angaben zur Person
+			</h2>
+
+			<div class="grid grid-cols-1 gap-5 md:grid-cols-2">
+				<div>
+					<label for="firstName" class="mb-1 block text-sm font-medium text-gray-700"
+						>Vorname *</label
+					>
+					<input
+						id="firstName"
+						name="firstName"
+						type="text"
+						required
+						class="block w-full rounded border border-gray-300 p-2 text-sm shadow-sm focus:border-brand-navy focus:ring-brand-navy"
+					/>
+				</div>
+
+				<div>
+					<label for="lastName" class="mb-1 block text-sm font-medium text-gray-700"
+						>Nachname *</label
+					>
+					<input
+						id="lastName"
+						name="lastName"
+						type="text"
+						required
+						class="block w-full rounded border border-gray-300 p-2 text-sm shadow-sm focus:border-brand-navy focus:ring-brand-navy"
+					/>
+				</div>
+
+				<div class="md:col-span-2">
+					<label for="alias" class="mb-1 block text-sm font-medium text-gray-700"
+						>Rufname / Alias</label
+					>
+					<input
+						id="alias"
+						name="alias"
+						type="text"
+						placeholder="z.B. Oma Frieda, Onkel Karl…"
+						class="block w-full rounded border border-gray-300 p-2 text-sm shadow-sm focus:border-brand-navy focus:ring-brand-navy"
+					/>
+				</div>
+			</div>
+		</div>
+
+		<!-- Sticky Save Bar -->
+		<div
+			class="sticky bottom-0 z-10 -mx-4 flex items-center justify-between border-t border-brand-sand bg-white px-6 py-4 shadow-[0_-2px_8px_rgba(0,0,0,0.06)]"
+		>
+			<a
+				href="/persons"
+				class="text-sm font-medium text-gray-500 transition-colors hover:text-brand-navy"
+			>
+				Abbrechen
+			</a>
+			<button
+				type="submit"
+				class="rounded bg-brand-navy px-6 py-2 text-sm font-bold tracking-widest text-white uppercase transition-colors hover:bg-brand-navy/80"
+			>
+				Speichern
+			</button>
+		</div>
+	</form>
+</div>