fix: add category and favorites filters to all recipe pages

- Move categories logic into Search component for centralization
- Add isLoggedIn prop to SeasonLayout and IconLayout components
- Fix FilterPanel CSS to properly handle hidden favorites filter
- Fix FavoritesFilter to trigger onToggle when checkbox changes
- Update Search effect to track all filter states (category, tags, icon, season, favorites)
- Hide favorites filter on favorites page while maintaining proper grid layout
- All filters now work consistently across entire site

src/routes/[recipeLang=recipeLang]/icon/[icon]/+page.svelte

@@ -26,7 +26,7 @@
         return data.season.filter(r => matchedRecipeIds.has(r._id));
     });
 </script>
-<IconLayout icons={data.icons} active_icon={data.icon} routePrefix="/{data.recipeLang}" lang={data.lang} recipes={data.season} onSearchResults={handleSearchResults}>
+<IconLayout icons={data.icons} active_icon={data.icon} routePrefix="/{data.recipeLang}" lang={data.lang} recipes={data.season} isLoggedIn={!!data.session?.user} onSearchResults={handleSearchResults}>
 	{#snippet recipesSlot()}
 		<Recipes>
 			{#each rand_array(filteredRecipes) as recipe}