Refactor DTOs, add Blazor WASM frontend, enable CORS

- Split `CatalogDto` into `CatalogReadDto` and `CatalogWriteDto` for clear separation of read/write operations in both backend and frontend.
- Updated API controllers, services, and AutoMapper profiles to use new DTOs; ensured audit fields are set in service layer.
- Enabled CORS in the API project to support Blazor WASM frontend.
- Added new Blazor WebAssembly project (`DbFirst.BlazorWasm`) with catalog management UI, API client, Bootstrap v5.1.0 styling, and configuration-driven API base URL.
- Included `bootstrap.min.css` and its source map for frontend styling and easier debugging.
- Updated solution file to include new project and support multiple build configurations.
- Result: improved API design, clean DTO separation, and a modern interactive frontend for catalog management.

DbFirst.BlazorWasm/Models/CatalogReadDto.cs

@@ -0,0 +1,12 @@
+namespace DbFirst.BlazorWasm.Models;
+
+public class CatalogReadDto
+{
+    public int Guid { get; set; }
+    public string CatTitle { get; set; } = string.Empty;
+    public string CatString { get; set; } = string.Empty;
+    public string AddedWho { get; set; } = string.Empty;
+    public DateTime AddedWhen { get; set; }
+    public string? ChangedWho { get; set; }
+    public DateTime? ChangedWhen { get; set; }
+}

DbFirst.BlazorWasm/Models/CatalogWriteDto.cs

@@ -0,0 +1,7 @@
+namespace DbFirst.BlazorWasm.Models;
+
+public class CatalogWriteDto
+{
+    public string CatTitle { get; set; } = string.Empty;
+    public string CatString { get; set; } = string.Empty;
+}