[FMainz]

Summary

• Add active DHCP lease count with client details available as sensor attributes.
• Add cumulative traffic counters for the GREEN, ORANGE, and BLUE interfaces.
• Add reboot-required status and a combined count of available core and package updates.
• Update the English and German documentation and translations.
• Bump the integration version to 0.3.6.

These sensors require api.cgi from [IPFire-API](https://github.com/FMainz/IPFire-API).