Add initial ASP.NET Core project structure

This commit introduces the initial setup for the DigitalData.TaskFlow solution:
- Added `DigitalData.TaskFlow.sln` to organize the project structure into `src`, `presentation`, `core`, and `infrastructure` folders.
- Created `DigitalData.TaskFlow.API` project targeting .NET 8.0 with nullable reference types and Swagger/OpenAPI support.
- Added `Program.cs` to configure the ASP.NET Core application with services, middleware, and Swagger UI.
- Added `launchSettings.json` for development profiles and environment variables.
- Added `appsettings.json` and `appsettings.Development.json` for logging and configuration.

src/presentation/DigitalData.TaskFlow.API/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}