fix(recipes): address review feedback — shared type, design system tokens, test coverage

- Extract RecipeSummary type to $lib/recipes/types.ts (was duplicated in 3 files)
- Fix +page.svelte header link: replace Skeleton UI classes with design system tokens
- Fix h1: use font-[var(--font-display)] and correct size
- Fix FilterChipRow: text-[11px] → text-[13px] + tracking-[0.04em] per design system
- Fix RecipeCard metadata: text-[11px] → text-[12px] for readability
- Remove unused imports (vi, beforeEach, afterEach) from page.test.ts
- Add combined search + effort filter test
- Add reset-to-Alle filter test

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

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

@@ -1,14 +1,7 @@
 <script lang="ts">
 	import FilterChipRow from '$lib/recipes/FilterChipRow.svelte';
 	import RecipeGrid from '$lib/recipes/RecipeGrid.svelte';
-
-	type RecipeSummary = {
-		id: string;
-		name: string;
-		cookTimeMin?: number;
-		effort?: string;
-		heroImageUrl?: string;
-	};
+	import type { RecipeSummary } from '$lib/recipes/types';
 
 	let { data }: { data: { recipes: RecipeSummary[] } } = $props();
 
@@ -37,8 +30,8 @@
 
 <div class="p-6 space-y-4">
 	<div class="flex items-center justify-between">
-		<h1 class="text-2xl font-medium">Rezepte</h1>
-		<a href="/recipes/new" class="btn variant-filled-primary">Rezept hinzufügen</a>
+		<h1 class="font-[var(--font-display)] text-[28px] font-medium text-[var(--color-text)]">Rezepte</h1>
+		<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>
 
 	<input