fix(#3458): add missing swarm_name field to test AppState initializer

3643eccf added swarm_name: Option<Arc<str>> to AppState and updated
the production initializer, but not state_with_roster()'s test-only
one — main's --all-targets/test build has been broken since. None,
matching atlas's proposed shape: the roster/links tests this helper
backs don't read the display name, and the loading path already has
its own coverage (load_swarm_name_covers_missing_and_set).

Closes #3458.

swarm-controller/src/main.rs

@@ -1057,6 +1057,7 @@ mod tests {
             status: None,
             jobq: std::sync::Arc::clone(&sched),
             webhook_secret: None,
+            swarm_name: None,
         };
         (state, sched)
     }