Fix infinite recursion in get_by_cid

Remove self-recursive call that caused infinite loop when looking up IPFS CIDs.

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

cache_manager.py

@@ -428,10 +428,6 @@ class L1CacheManager:
     def get_by_cid(self, cid: str) -> Optional[Path]:
         """Get cached file path by cid or IPFS CID. Falls back to IPFS if not in local cache."""
 
-        # If it looks like an IPFS CID, use get_by_cid instead
-        if self._is_ipfs_cid(cid):
-            return self.get_by_cid(cid)
-
         # Check index first (Redis then local)
         node_id = self._get_content_index(cid)
         if node_id: