Enhance parseCIDR in utils/ipallowlist.go to support single IP addresses
(without CIDR prefix) and ensure IP is in canonical form. This matches
the functionality previously in access.go.
- Add ParseCIDR as public function supporting CIDR and single IP
- Update access.go to use utils.ParseCIDR instead of local implementation
- Remove duplicate parseCIDR function from access.go
- Update tests to use utils.ParseCIDR
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>