fix(chain): correct multi-hop detection for hops=None from JSON

The check `getattr(op, 'hops', 1) != 1` incorrectly detected multi-hop
when hops was None (from JSON deserialization), since None != 1 is True.

Fixed to explicitly check for non-None and non-1 values.

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

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

Author: lmeyerov

graphistry/compute/chain.py

@@ -225,7 +225,7 @@ def combine_steps(
         # Multi-hop edges span multiple nodes, so simple endpoint filtering doesn't work
         has_multihop = any(
             isinstance(op, ASTEdge) and (
-                getattr(op, 'hops', 1) != 1 or
+                (getattr(op, 'hops', None) is not None and getattr(op, 'hops', None) != 1) or
                 getattr(op, 'min_hops', None) is not None or
                 getattr(op, 'max_hops', None) is not None or
                 getattr(op, 'to_fixed_point', False)