fix(anthropic): tool_choice 'none' still allowed tool calls

When tool_choice was 'none', the code did 'pass' — no tool_choice
was sent but tools were still included in the request. Anthropic
defaults to 'auto' when tools are present, so the model could still
call tools despite the caller requesting 'none'.

Fix: omit tools entirely from the request when tool_choice is 'none',
which is the only way to prevent tool use with the Anthropic API.

agent/anthropic_adapter.py

@@ -1053,7 +1053,8 @@ def build_anthropic_kwargs(
         elif tool_choice == "required":
             kwargs["tool_choice"] = {"type": "any"}
         elif tool_choice == "none":
-            pass  # Don't send tool_choice — Anthropic will use tools if needed
+            # Anthropic has no tool_choice "none" — omit tools entirely to prevent use
+            kwargs.pop("tools", None)
         elif isinstance(tool_choice, str):
             # Specific tool name
             kwargs["tool_choice"] = {"type": "tool", "name": tool_choice}