feat(recipes): add RecipeGrid with 2/4-col responsive grid and empty state

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

frontend/src/lib/recipes/RecipeGrid.svelte

@@ -0,0 +1,22 @@
+<script lang="ts">
+	import RecipeCard from './RecipeCard.svelte';
+
+	type RecipeSummary = { id: string; name: string; cookTimeMin?: number; effort?: string; heroImageUrl?: string };
+
+	let { recipes }: { recipes: RecipeSummary[] } = $props();
+</script>
+
+{#if recipes.length > 0}
+	<div data-testid="recipe-grid" class="grid grid-cols-2 lg:grid-cols-4 gap-[8px] lg:gap-[12px] p-[16px]">
+		{#each recipes as recipe (recipe.id)}
+			<RecipeCard {recipe} compact={true} />
+		{/each}
+	</div>
+{:else}
+	<div class="flex flex-col items-center justify-center py-[48px] px-[24px] text-center">
+		<p class="text-[var(--color-text-muted)] text-[14px] mb-[16px]">Noch keine Rezepte vorhanden.</p>
+		<a href="/recipes/new" class="font-sans text-[13px] font-medium tracking-[0.04em] rounded-[var(--radius-md)] bg-[var(--green-dark)] px-[24px] py-[12px] text-white">
+			Rezept hinzufügen
+		</a>
+	</div>
+{/if}