Fix recipe_id to use IPFS CID instead of local hash

The recipe upload was returning the SHA3-256 hash from artdag's cache
instead of the IPFS CID, causing recipe lookups to fail.

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

app/services/recipe_service.py

@@ -114,7 +114,7 @@ class RecipeService:
 
             # Store in cache (content-addressed, auto-pins to IPFS)
             cached, ipfs_cid = self.cache.put(tmp_path, node_type="recipe", move=True)
-            recipe_id = cached.cid
+            recipe_id = ipfs_cid or cached.cid  # Prefer IPFS CID
 
             return recipe_id, None