fix(mux/rust): prevent multiple instances via fd-lock (v0.1.1)

mux/rust/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "donglora-mux"
-version = "0.1.0"
+version = "0.1.1"
 edition = "2024"
 authors = ["Stephen Waits <steve@waits.net>"]
 license = "MIT"
@@ -18,6 +18,7 @@ tokio-serial = "5"
 tokio-util = "0.7"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+fd-lock = "4"
 
 [lints.clippy]
 unwrap_used = "deny"