Only show networks in side bar if a mounter is found

src/app.rs

@@ -671,6 +671,7 @@ impl App {
                 .divider_above()
         });
 
+        if !self.mounters.is_empty() {
             nav_model = nav_model.insert(|b| {
                 b.text(fl!("networks"))
                     .icon(widget::icon::icon(
@@ -684,6 +685,7 @@ impl App {
                     ))
                     .divider_above()
             });
+        }
 
         // Collect all mounter items
         let mut nav_items = Vec::new();