Refactor dashboard navigation, catalog grid, and API client

- Add sidebar dashboard navigation and support multiple dashboards
- Extract catalog grid/form logic to reusable CatalogsGrid component
- Add CatalogApiClient and DTOs for catalog CRUD operations
- Define dashboards with JSON data sources (Default, CatalogsGrid)
- Update configuration for dashboard and API endpoints
- Improve styling and imports for modularity and maintainability

DbFirst.BlazorWebApp/Program.cs

@@ -1,4 +1,5 @@
 using DbFirst.BlazorWebApp.Components;
+using DbFirst.BlazorWebApp.Services;
 using DevExpress.Blazor;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -9,6 +10,19 @@ builder.Services.AddRazorComponents()
 
 builder.Services.AddDevExpressBlazor();
 
+var apiBaseUrl = builder.Configuration["ApiBaseUrl"];
+if (!string.IsNullOrWhiteSpace(apiBaseUrl))
+{
+    builder.Services.AddHttpClient<CatalogApiClient>(client =>
+    {
+        client.BaseAddress = new Uri(apiBaseUrl);
+    });
+}
+else
+{
+    builder.Services.AddHttpClient<CatalogApiClient>();
+}
+
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.