Do not fail login when push device registration fails

register_push_device() runs on re-authentication of an existing device
in authenticated_response(). Its error was propagated with `?`, so a
failure talking to the push relay/identity server (e.g. an undecodable
response in get_auth_api_token(), "Unexpected push token received from
bitwarden server") turned a successful authentication into a 400 Bad
Request on POST /identity/connect/token.

Handle the registration best-effort instead: log the error and continue,
mirroring the new-device login email handling a few lines above. The
device is still saved afterwards, and a re-login no longer fails when the
push relay/identity endpoint misbehaves.

Fixes #7371

src/api/identity.rs

@@ -493,7 +493,12 @@ async fn authenticated_response(
 
     // register push device
     if !device.is_new() {
-        register_push_device(device, conn).await?;
+        // Registering the device for push is best-effort: a failure talking to the
+        // push relay/identity server must not turn a successful authentication into
+        // an error (see #7371). This mirrors the new-device email handling above.
+        if let Err(e) = register_push_device(device, conn).await {
+            error!("An error occurred while registering the device for push notifications: {e}");
+        }
     }
 
     // Save to update `device.updated_at` to track usage and toggle new status