refactor: use explicit empty array type for Windows service start arguments

Replace inline empty array literal with explicitly typed empty_args variable to satisfy Rust type inference requirements for service.start() call.

desktop-client/tunnel-helper/src/main.rs

@@ -260,7 +260,8 @@ fn install_windows_service() -> Result<(), String> {
         })
         .map_err(|err| format!("Unable to install NexaVPN tunnel service: {err}"))?;
 
-    let _ = service.start(&[]);
+    let empty_args: [&str; 0] = [];
+    let _ = service.start(&empty_args);
     Ok(())
 }