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.BlazorWasm/Layout/NavMenu.razor

@@ -22,8 +22,8 @@
             </NavLink>
         </div>
         <div class="nav-item px-3">
-            <NavLink class="nav-link" href="dashboard">
-                <span class="oi oi-list-rich" aria-hidden="true"></span> Web Dashboard
+            <NavLink class="nav-link" href="dashboards/default">
+                <span class="oi oi-list-rich" aria-hidden="true"></span> Dashboards
             </NavLink>
         </div>
     </nav>