feat: add Anthropic effort level support for Claude models

Add effort parameter (high/medium/low) for Claude 4.5+ and 4.6 models,
consistent with OpenAI reasoning_effort and Google thinking_level.
Also add content normalization for Anthropic responses.

tradingagents/graph/trading_graph.py

@@ -148,6 +148,11 @@ class TradingAgentsGraph:
             if reasoning_effort:
                 kwargs["reasoning_effort"] = reasoning_effort
 
+        elif provider == "anthropic":
+            effort = self.config.get("anthropic_effort")
+            if effort:
+                kwargs["effort"] = effort
+
         return kwargs
 
     def _create_tool_nodes(self) -> Dict[str, ToolNode]: