Multiple test mock structs across 5 files implement `GetBlockHeightByTime` and `StateSyncEventsAtHeight` as extra methods that are not declared in either the `IHeimdallClient` or `Endpoint` interface, making these stubs unreachable dead code. These are leftovers from an earlier two-step design iteration (get Heimdall height, then fetch by height) that was replaced by the unified `StateSyncEventsByTime` call; removing them would avoid falsely implying that failover test coverage exists for an AtH