feat: public/private view separation + profile favorites

- Hide time, favorites heart, recipe counter, random buttons for guests
- Move favorites section from HomePage to ProfilePage (personal)
- Make avatar button clickable → login (guest) / profile (logged in)
- Show user avatar in top bar when available
- Add Airfryer category

frontend/src/components/recipe/RecipeCard.tsx

@@ -2,6 +2,7 @@ import { Link } from 'react-router'
 import { Heart, Clock } from 'lucide-react'
 import { useMutation, useQueryClient } from '@tanstack/react-query'
 import { toggleFavorite } from '../../api/recipes'
+import { useAuth } from '../../context/AuthContext'
 import type { Recipe } from '../../api/types'
 
 const gradients = [
@@ -12,6 +13,7 @@ const gradients = [
 ]
 
 export function RecipeCard({ recipe }: { recipe: Recipe }) {
+  const { isAuthenticated } = useAuth()
   const qc = useQueryClient()
   const favMutation = useMutation({
     mutationFn: () => toggleFavorite(recipe.id),
@@ -36,22 +38,24 @@ export function RecipeCard({ recipe }: { recipe: Recipe }) {
         <Link to={`/recipe/${recipe.slug}`}>
           <h3 className="font-display text-base sm:text-lg text-espresso line-clamp-2">{recipe.title}</h3>
         </Link>
-        <div className="flex items-center justify-between mt-2">
-          {totalTime > 0 && (
-            <span className="flex items-center gap-1 text-warm-grey text-xs">
-              <Clock size={14} /> {totalTime} min
-            </span>
-          )}
-          <button
-            onClick={(e) => { e.preventDefault(); e.stopPropagation(); favMutation.mutate() }}
-            className="ml-auto p-2 -mr-2 min-w-[44px] min-h-[44px] flex items-center justify-center active:scale-125 transition-transform"
-          >
-            <Heart
-              size={22}
-              className={recipe.is_favorite ? 'fill-primary text-primary' : 'text-warm-grey'}
-            />
-          </button>
-        </div>
+        {isAuthenticated && (
+          <div className="flex items-center justify-between mt-2">
+            {totalTime > 0 && (
+              <span className="flex items-center gap-1 text-warm-grey text-xs">
+                <Clock size={14} /> {totalTime} min
+              </span>
+            )}
+            <button
+              onClick={(e) => { e.preventDefault(); e.stopPropagation(); favMutation.mutate() }}
+              className="ml-auto p-2 -mr-2 min-w-[44px] min-h-[44px] flex items-center justify-center active:scale-125 transition-transform"
+            >
+              <Heart
+                size={22}
+                className={recipe.is_favorite ? 'fill-primary text-primary' : 'text-warm-grey'}
+              />
+            </button>
+          </div>
+        )}
       </div>
     </div>
   )