fix: carry switch_code through WebRTC relay fallbacks after rebase

The rebase onto master (switch-code feature) added an 8th request_relay
parameter; pass the interface's switch code from both WebRTC->relay
fallback paths so a role-swap session survives the fallback. Also drop
a duplicate bindgen 0.72.1 entry the Cargo.lock merge produced.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ExUfAkYbq8UC9pQCiLy8TQ

src/client.rs

@@ -1070,6 +1070,7 @@ impl Client {
                                     &key,
                                     &token,
                                     conn_type,
+                                    &interface.get_switch_code(),
                                 )
                                 .await
                                 .map_err(|relay_e| {
@@ -1405,6 +1406,7 @@ impl Client {
                     key,
                     token,
                     conn_type,
+                    &interface.get_switch_code(),
                 )
                 .await
                 {