Fix client stats: shared BandwidthState survives timeout cancellation

The state is now created in main.rs and passed into run_client, so
when --duration timeout cancels the future, the stats are still
accessible via shared_state.summary(). CSV and syslog now show
real speeds and byte counts.

Verified: TCP loopback shows 32 Gbps in CSV output.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/ecsrp5_test.rs

@@ -85,6 +85,7 @@ async fn test_ecsrp5_full_client_auth() {
             Some("testuser".into()),
             Some("testpass".into()),
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -109,6 +110,7 @@ async fn test_ecsrp5_wrong_password_fails() {
         Some("testuser".into()),
         Some("wrongpass".into()),
         false,
+        btest_rs::bandwidth::BandwidthState::new(),
     )
     .await;
 
@@ -131,6 +133,7 @@ async fn test_md5_auth_still_works() {
             Some("testuser".into()),
             Some("testpass".into()),
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -155,6 +158,7 @@ async fn test_noauth_still_works() {
             None,
             None,
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -179,6 +183,7 @@ async fn test_ecsrp5_udp_bidirectional() {
             Some("testuser".into()),
             Some("testpass".into()),
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });

tests/integration_test.rs

@@ -153,6 +153,7 @@ async fn test_loopback_tcp_rx() {
             None,
             None,
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -177,6 +178,7 @@ async fn test_loopback_tcp_tx() {
             None,
             None,
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -201,6 +203,7 @@ async fn test_loopback_tcp_both() {
             None,
             None,
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });
@@ -225,6 +228,7 @@ async fn test_loopback_tcp_with_auth() {
             Some("admin".into()),
             Some("secret".into()),
             false,
+            btest_rs::bandwidth::BandwidthState::new(),
         )
         .await
     });