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.infrastructure/Persistence/UnitOfWork.cs

@@ -0,0 +1,28 @@
+using Mws.Application.Common;
+using Mws.Application.Common.Repositories;
+using Mws.Infrastructure.Persistence.Repositories;
+
+namespace Mws.Infrastructure.Persistence;
+
+public class UnitOfWork : IUnitOfWork
+{
+    private readonly AppDbContext _db;
+
+    public UnitOfWork(AppDbContext db)
+    {
+        _db = db;
+        Users = new UserRepository(db);
+        Projects = new ProjectRepository(db);
+        Tasks = new TaskRepository(db);
+        Documents = new DocumentRepository(db);
+        Roles = new RoleRepository(db);
+    }
+
+    public IUserRepository Users { get; }
+    public IProjectRepository Projects { get; }
+    public ITaskRepository Tasks { get; }
+    public IDocumentRepository Documents { get; }
+    public IRoleRepository Roles { get; }
+
+    public Task<int> SaveChangesAsync(CancellationToken ct = default) => _db.SaveChangesAsync(ct);
+}