style: remove unused synchronization imports

Eliminate unused Arc, Mutex, and RwLock imports to clean up codebase and reduce compiler warnings.

src/baseliner.rs

@@ -9,7 +9,6 @@ use std::collections::HashMap;
 use std::net::IpAddr;
 use std::sync::atomic::Ordering;
 use std::sync::mpsc::{Receiver, Sender};
-use std::sync::{Arc, Mutex};
 use std::time::Instant;
 
 #[derive(Copy, Clone)]