Handle zero-capacity cache safely

[fallintoplace]

Summary

Treat a cache capacity of 0 as an explicitly disabled cache instead of entering CAR replacement on the first insert.

Details

CacheSettings::with_capacity(0) can currently build a CarCache with empty clock lists. On the first cache miss, put sees len == capacity, calls replace, and the clock hand can advance with modulo zero.

This keeps the existing usize API intact and makes the compatible behavior explicit: capacity 0 stores no entries and returns cache misses.

Validation

• cargo test -p nv-redfish-bmc-http

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.