Commit MWS backend source tree

The ASP.NET Core solution (mws.api/mws.application/mws.domain/
mws.infrastructure) existed only as untracked working files. Adding
it to version control, plus a .gitignore for build output and local
tooling directories, so the CQRS/mediator refactor plan has a real
git history to branch and diff against.

mws.application/Permissions/IPermissionService.cs

@@ -0,0 +1,7 @@
+namespace Mws.Application.Permissions;
+
+public interface IPermissionService
+{
+    Task<List<MenuItemDto>> GetMenuAsync(Guid userId, CancellationToken ct = default);
+    Task EnsureAsync(Guid userId, string screen, PermissionAction action, CancellationToken ct = default);
+}