fix: improve Quick Actions sidebar layout and text visibility

feat: make whats-new signature configurable via config and .env

feat: Complete admin panel with Tailwind CSS and configurable routes

- Added comprehensive admin dashboard with statistics and quick actions
- Implemented Tailwind CSS design system throughout admin panel
- Created configurable route system with environment variables
- Added RouteHelper class for consistent route name generation
- Fixed dashboard quick actions with proper styling and hover effects
- Updated all views to use simplified route naming (version-manager.*)
- Added Users and Analytics pages with Vue 3 interactivity
- Created admin layout with sidebar navigation
- Added comprehensive configuration documentation
- Implemented responsive design with modern UI components
- Added system status indicators and latest versions timeline
- Updated all controllers to use new route structure