Implement dark mode support using a new ThemeState service that manages theme switching and integrates with DevExpress Blazor theming. Update App.razor to apply the theme globally, enhance MainLayout with a toggle button and dynamic CSS classes, and add dark mode styles to CSS files. Register ThemeState as a scoped service in Program.cs.
Added new Blazor Server project `DbFirst.BlazorWebApp` with core UI components, pages, and static assets. Updated solution file to include the project. Also added `bootstrap.min.css.map` to support CSS debugging in browser developer tools.
