Zoho throttling is account/plan-dependent; measurements show a
sustainable listing rate of ~6 requests/s on a production account -
going faster drains a token bucket and stalls ~2 minutes per
Retry-After, which is strictly slower overall. Add per-remote pacer
options (default 6/1) using the same token-bucket pacer as the Google
Drive backend. Set --zoho-tpslimit 0 to disable the cap.
See #9570
