- Add support for IPv6 networks in firewall rule generation and validation.
- Add --docker-subnets [SUBNET1 SUBNET2 ...] option to `ufw-docker install` and `ufw-docker check`.
- When used without arguments, automatically detects and applies all Docker network subnets.
- When given subnet arguments, applies firewall rules only to specified subnets (supports multiple subnets, including non-Docker-managed networks).
- If not specified, falls back to default RFC1918 IPv4 and fd00::/8 IPv6 subnets.
- Improve help output with detailed examples and usage guidance.