Add favorite indicators to recipe cards and improve favorites UI

- Add heart emoji indicators to recipe cards (top-left positioning)
- Show favorites across all recipe list pages (season, category, icon, tag)
- Create favorites utility functions for server-side data merging
- Convert client-side load files to server-side for session access
- Redesign favorite button with emoji hearts (🖤/❤️) and bottom-right positioning
- Fix randomizer array mutation issue causing card display glitches
- Implement consistent favorite indicators with drop shadows for visibility

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/routes/rezepte/icon/[icon]/+page.svelte

@@ -11,7 +11,7 @@
 <IconLayout icons={data.icons} active_icon={data.icon} >
 <Recipes slot=recipes>
 	{#each rand_array(data.season) as recipe}
-		<Card {recipe} icon_override=true></Card>
+		<Card {recipe} icon_override=true isFavorite={recipe.isFavorite} showFavoriteIndicator={!!data.session?.user}></Card>
 	{/each}
 </Recipes>
 </IconLayout>