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/favorites/+page.svelte

@@ -47,7 +47,7 @@ h1{
 {:else if data.favorites.length > 0}
     <Recipes>
         {#each data.favorites as recipe}
-            <Card {recipe} {current_month}></Card>
+            <Card {recipe} {current_month} isFavorite={true} showFavoriteIndicator={true}></Card>
         {/each}
     </Recipes>
 {:else}