Per-server themes, update indicator & docker-run converter

• Themes per server: five harmonised colour palettes (Classic Blue, Sunset, Forest, Ocean, Monochrome) selectable per Dockge instance
• Update indicator in the stack list: on Dockge-Enhanced an orange pill marks every stack with a pending image update
• Server switching right from the stack overview via a menu in the navigation title
• docker run → compose converter: paste a »docker run« command when creating a stack to translate it locally into a compose.yaml
• Multiple Dockge instances per SSH host: one SSH access shared between a publicly exposed and a local-only Dockge instance running on the same machine
• ISO-8601 timestamps in container logs (Dockge-Enhanced)
• Fixed: tapping a stack reliably opens the detail view again after a server switch or longer time in the background
• Fixed: sheet reset on server switch consistently clears all bindings
• Fixed: update pill disappears the moment you trigger the update and only comes back when the watcher actually finds a new image