refactor(nav): Pfeil-Icon im Header statt großem Zurück-Pill

Der neu eingefügte Admin-Pill war zu prominent für seinen Zweck. Raus
damit. Stattdessen zeigt der Haupt-Header auf allen Nicht-Hauptseiten
links einen ArrowLeft-Icon-Link zur Startseite — platzsparend und
konsistent über alle Sub-Seiten (Admin, Rezept, Preview, Wunschliste…).
Auf der Startseite selbst bleibt das „Kochwas"-Wortmarke stehen.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/routes/+layout.svelte

@@ -2,7 +2,7 @@
   import { onMount } from 'svelte';
   import { page } from '$app/stores';
   import { goto, afterNavigate } from '$app/navigation';
-  import { Settings, CookingPot, Utensils, Menu, BookOpen } from 'lucide-svelte';
+  import { Settings, CookingPot, Utensils, Menu, BookOpen, ArrowLeft } from 'lucide-svelte';
   import { profileStore } from '$lib/client/profile.svelte';
   import { wishlistStore } from '$lib/client/wishlist.svelte';
   import { pwaStore } from '$lib/client/pwa.svelte';
@@ -216,7 +216,13 @@
 
 <header class="bar">
   <div class="bar-inner">
-    <a href="/" class="brand">Kochwas</a>
+    {#if $page.url.pathname === '/'}
+      <a href="/" class="brand">Kochwas</a>
+    {:else}
+      <a href="/" class="home-back" aria-label="Zurück zur Startseite">
+        <ArrowLeft size={22} strokeWidth={2} />
+      </a>
+    {/if}
     {#if showHeaderSearch}
       <div class="nav-search-wrap" bind:this={navContainer}>
         <form class="nav-search" onsubmit={submitNav} role="search">
@@ -407,6 +413,20 @@
     color: #2b6a3d;
     flex-shrink: 0;
   }
+  .home-back {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 40px;
+    height: 40px;
+    border-radius: 999px;
+    color: #2b6a3d;
+    text-decoration: none;
+    flex-shrink: 0;
+  }
+  .home-back:hover {
+    background: #f4f8f5;
+  }
   .nav-search-wrap {
     position: relative;
     flex: 1;

src/routes/admin/+layout.svelte

@@ -1,6 +1,5 @@
 <script lang="ts">
   import { page } from '$app/stores';
-  import { ArrowLeft } from 'lucide-svelte';
 
   let { children } = $props();
 
@@ -12,10 +11,6 @@
 </script>
 
 <nav class="tabs">
-  <a href="/" class="back" aria-label="Zurück zu Kochwas">
-    <ArrowLeft size={18} strokeWidth={2} />
-    <span>Zurück</span>
-  </a>
   {#each items as item (item.href)}
     <a
       href={item.href}
@@ -57,25 +52,6 @@
     color: white;
     border-color: #2b6a3d;
   }
-  .back {
-    display: inline-flex;
-    align-items: center;
-    gap: 0.4rem;
-    padding: 0.6rem 0.85rem 0.6rem 0.7rem;
-    background: white;
-    border: 1px solid #e4eae7;
-    border-radius: 999px;
-    text-decoration: none;
-    color: #2b6a3d;
-    font-size: 0.9rem;
-    font-weight: 600;
-    white-space: nowrap;
-    min-height: 40px;
-    flex-shrink: 0;
-  }
-  .back:hover {
-    background: #eaf4ed;
-  }
   .admin-body {
     padding: 1rem 0;
   }