Apply cargo fmt to node module and handshake tests

Exposed by the rustfmt toolchain-pin fix now that rustfmt runs under
the pinned 1.94.1 toolchain in CI. Mechanical formatting changes:

- src/node/mod.rs: collapse EthernetTransport::new let-binding onto
  one line (fits within width limit)
- src/node/tests/handshake.rs: reorder imports (super::* after
  specific import) and expand two assert_eq! calls to multi-line form

src/node/mod.rs

@@ -734,8 +734,7 @@ impl Node {
 
             for (name, eth_config) in eth_instances {
                 let transport_id = self.allocate_transport_id();
-                let eth =
-                    EthernetTransport::new(transport_id, name, eth_config, packet_tx.clone());
+                let eth = EthernetTransport::new(transport_id, name, eth_config, packet_tx.clone());
                 transports.push(TransportHandle::Ethernet(eth));
             }
         }

src/node/tests/handshake.rs

@@ -1,7 +1,7 @@
 //! Integration tests for end-to-end Noise XX handshake scenarios.
 
-use super::*;
 use super::spanning_tree::{cleanup_nodes, drain_all_packets, initiate_handshake, make_test_node};
+use super::*;
 
 #[tokio::test]
 async fn test_two_node_handshake_udp() {
@@ -1089,8 +1089,16 @@ async fn test_xx_duplicate_msg1_resends_msg2() {
     };
     node_b.handle_msg1(first_packet).await;
 
-    assert_eq!(node_b.connection_count(), 1, "B: 1 connection after first msg1");
-    assert_eq!(node_b.peer_count(), 0, "B: 0 peers (XX, no promotion at msg1)");
+    assert_eq!(
+        node_b.connection_count(),
+        1,
+        "B: 1 connection after first msg1"
+    );
+    assert_eq!(
+        node_b.peer_count(),
+        0,
+        "B: 0 peers (XX, no promotion at msg1)"
+    );
 
     // Duplicate msg1 from same address → dedup triggers msg2 resend, not new handshake
     let dup_packet = ReceivedPacket {