feat: upgrade to donglora-client 0.2, fix org URLs, publish-ready

- Upgrade donglora-client from 0.1 (monorepo path dep) to 0.2 (crates.io)
- Import wire-level constants from donglora_client::protocol::*
- Fix repository URL to github.com/donglora/mux-rs
- Add homepage, rust-version, exclude to Cargo.toml
- Fix README (remove monorepo paths, add install instructions)
- Allow clippy unwrap in test module

src/main.rs

@@ -61,9 +61,7 @@ async fn main() -> anyhow::Result<()> {
     };
 
     // Resolve socket path
-    let socket_path = args
-        .socket
-        .unwrap_or_else(donglora_client::default_socket_path);
+    let socket_path = args.socket.unwrap_or_else(donglora_client::default_socket_path);
 
     // Parse TCP address
     let tcp_addr = parse_tcp_addr(&args.tcp);