chore: Remove unused DEFAULT_FALSE constant from agent_graph

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jsonbailey

packages/sdk/server-ai/src/ldai/agent_graph/__init__.py

@@ -4,11 +4,9 @@
 
 from ldclient import Context
 
-from ldai.models import AIAgentConfig, AIAgentConfigDefault, AIAgentGraphConfig, Edge
+from ldai.models import AIAgentConfig, AIAgentGraphConfig, Edge
 from ldai.tracker import AIGraphTracker
 
-DEFAULT_FALSE = AIAgentConfigDefault(enabled=False)
-
 
 class AgentGraphNode:
     """