feat(recipes): add /recipes/new route with create action

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

frontend/src/routes/(app)/recipes/new/+page.svelte

@@ -0,0 +1,17 @@
+<script lang="ts">
+	import RecipeForm from '$lib/recipes/RecipeForm.svelte';
+	import type { PageData } from './$types';
+
+	let { data }: { data: PageData } = $props();
+</script>
+
+<svelte:head>
+	<title>Neues Rezept — Mealplan</title>
+</svelte:head>
+
+<div class="p-[24px]">
+	<h1 class="font-[var(--font-display)] text-[24px] md:text-[28px] font-medium text-[var(--color-text)] mb-[24px]">
+		Neues Rezept
+	</h1>
+	<RecipeForm recipe={data.recipe} categories={data.categories} action="?/create" />
+</div>