fix(staples): apply design-system styles to nav links and settings heading

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

frontend/src/routes/household/staples/+page.svelte

@@ -32,14 +32,20 @@
 
 			<!-- Footer navigation -->
 			<div class="flex justify-between p-6">
-				<a href="/planner">Überspringen</a>
-				<a href="/household/invite">Weiter</a>
+				<a
+					href="/planner"
+					class="font-sans text-[13px] font-medium tracking-[0.04em] text-[var(--color-text-muted)] hover:text-[var(--color-text)]"
+				>Überspringen</a>
+				<a
+					href="/household/invite"
+					class="font-sans text-[13px] font-medium tracking-[0.04em] rounded-[var(--radius-md)] bg-[var(--green-dark)] px-[24px] py-[12px] text-white"
+				>Weiter</a>
 			</div>
 		</main>
 	</div>
 {:else}
 	<div class="flex min-h-screen flex-col bg-[var(--color-page)]">
-		<h1>Vorräte</h1>
+		<h1 class="mb-[8px] font-[var(--font-display)] text-[18px] font-medium md:text-[28px] text-[var(--color-text)]">Vorräte</h1>
 		<StaplesManager categories={data.categories} context="settings" />
 	</div>
 {/if}