feat: Add CIDR calculator tool

[am2rican5]

Summary

• Add cidr command for computing network information from CIDR notation
• Display comprehensive network details including addresses in multiple formats (string, decimal, hex)
• Update README with usage examples

Features

Given a CIDR like 192.168.1.100/24, the tool displays:

• Address (input IP) in string, decimal, and dotted hex
• Network and broadcast addresses
• First/last usable host IPs
• Total host count
• Prefix length, netmask, and wildcard mask

Example

$ ut cidr 192.168.1.100/24

address           192.168.1.100
address_decimal   3232235876
address_hex       C0.A8.01.64
network           192.168.1.0
broadcast         192.168.1.255
first_host        192.168.1.1
last_host         192.168.1.254
total_hosts       254
prefix            24
netmask           255.255.255.0
netmask_hex       FF.FF.FF.00
wildcard          0.0.0.255
wildcard_hex      00.00.00.FF

[ksdme]

It makes more sense to put this tool under ip cidr namespace. So something like ut ip cidr info 192.168.1.100/24. This will let us do things like cidr contains etc.

[ksdme]

The tool should be available under ut ip cidr describe 192.168.1.100/24. Thanks for the contribution @am2rican5!

[am2rican5]

Awesome, thanks! Happy to contribute to the project.