Function execute_tool_calls 

pub async fn execute_tool_calls(
    calls: &[PendingToolCall],
    tools: &[Arc<dyn Tool>],
    ctx: &ToolContext,
    permission_checker: &PermissionChecker,
) -> Vec<ToolCallResult>

Execute a batch of tool calls, respecting concurrency constraints.

Tools that are concurrency-safe run in parallel. Other tools run serially. Results are returned in the same order as the input.