feat: Support absolute and relative stdio paths

crates/mcp-client/src/transport/stdio.rs

@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 use tokio::process::{Child, ChildStderr, ChildStdin, ChildStdout, Command};
-use std::path::{Path, PathBuf};
+use std::path::Path;
 
 use async_trait::async_trait;
 use mcp_core::protocol::JsonRpcMessage;