Two chokepoints per P0-2: WorkerClient.InvokeTimedAsync(<T>) wraps all 63
_hub.InvokeAsync call sites (plus TryInvokeAsync), and Stopwatch blocks
around the Island VMs' bulk DB load/write paths (list load, task list load,
reorders, batch delete, reconcile tick, count refresh). Single-row reads
stay untouched per the plan's rule of thumb. No display, no behavior change.
