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/PermissionService.cs

@@ -0,0 +1,47 @@
+using Mws.Application.Common;
+
+namespace Mws.Application.Permissions;
+
+public class PermissionService(IUnitOfWork uow) : IPermissionService
+{
+    public async Task<List<MenuItemDto>> GetMenuAsync(Guid userId, CancellationToken ct = default)
+    {
+        var roleId = await uow.Users.GetRoleIdAsync(userId, ct);
+        var permissions = await uow.Roles.GetPermissionsAsync(roleId, ct);
+
+        return ScreenCatalog.Screens.Select(s =>
+        {
+            permissions.TryGetValue(s.Key, out var p);
+            return new MenuItemDto
+            {
+                Key = s.Key,
+                Label = s.Label,
+                Path = s.Path,
+                CanView = p?.CanView ?? false,
+                CanCreate = p?.CanCreate ?? false,
+                CanEdit = p?.CanEdit ?? false,
+                CanDelete = p?.CanDelete ?? false,
+            };
+        }).ToList();
+    }
+
+    public async Task EnsureAsync(Guid userId, string screen, PermissionAction action, CancellationToken ct = default)
+    {
+        var roleId = await uow.Users.GetRoleIdAsync(userId, ct);
+        var permission = await uow.Roles.GetPermissionAsync(roleId, screen, ct);
+
+        var allowed = action switch
+        {
+            PermissionAction.View => permission?.CanView ?? false,
+            PermissionAction.Create => permission?.CanCreate ?? false,
+            PermissionAction.Edit => permission?.CanEdit ?? false,
+            PermissionAction.Delete => permission?.CanDelete ?? false,
+            _ => false,
+        };
+
+        if (!allowed)
+        {
+            throw new ForbiddenException($"Not permitted to {action} on {screen}");
+        }
+    }
+}