Add cookbook recipe import to shopping list with deduplication and quantity merging

app/templates/recipe_detail.html

@@ -24,6 +24,9 @@
         <span id="cookmode-nav-badge" class="cb-badge-pill">Aus</span>
       </button>
       {% if not is_shared %}
+        <a href="/shopping-list?import_recipe_id={{ recipe.id }}" class="cb-btn cb-btn-outline" title="Zutaten auf die Einkaufsliste übernehmen">
+          <span>🛒</span> <span>Auf Einkaufsliste</span>
+        </a>
         <a href="/cookbook" class="cb-btn cb-btn-outline">
           <span>📖</span> <span>Alle Rezepte</span>
         </a>
@@ -65,6 +68,9 @@
         </button>
         <hr class="cb-mobile-divider">
         {% if not is_shared %}
+          <a href="/shopping-list?import_recipe_id={{ recipe.id }}" class="cb-mobile-item">
+            <span>🛒</span> <span>Auf Einkaufsliste</span>
+          </a>
           <button type="button" onclick="openShareModal()" class="cb-mobile-item">
             <span>🔗</span> <span>Rezept teilen</span>
           </button>