Replace async goroutine-based cleanup with a synchronous flow where
Start runs cleanup inline after renewLoop exits. Use a stopCtx channel
so GracefullyStop can pass its deadline-bounded context to Start's
cleanup path. When no graceful stop occurs, Start fires cleanup in a
background goroutine with a 10s timeout.
Also fix GetMapping double Lock, renewMapping referencing undefined m.mu,
cleanup referencing undefined variables, remove statemanager dependency,
and align manager_js.go stub signatures.
4d6b810f8b