Fix undefined cache_manager in clear_user_data

Call get_cache_manager() to get the cache manager instance
before using it in effects and media deletion.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/routers/home.py

@@ -133,6 +133,7 @@ async def clear_user_data(request: Request):
         errors.append(f"Failed to list recipes: {e}")
 
     # Delete all effects (uses ownership model)
+    cache_manager = get_cache_manager()
     try:
         # Get user's effects from item_types
         effect_items = await database.get_user_items(actor_id, item_type="effect", limit=10000)