Replace DockerIcon (Simple Icons) with lucide-solid's Container icon to maintain consistency with other navigation icons (Server, HardDrive, Mail). All icons now use the same stroke-based style and rendering pattern.
Add Docker tab to the settings section navigation using the same DockerIcon component used in the main navigation. The icon is rendered at w-4 h-4 to match the visual weight of the lucide icons at size 16.
Now the settings navigation shows: Virtual Environment, Backup Server, Mail Gateway, and Docker.