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/ScreenCatalog.cs

@@ -0,0 +1,18 @@
+namespace Mws.Application.Permissions;
+
+public record ScreenDefinition(string Key, string Label, string Path);
+
+public static class ScreenCatalog
+{
+    public static readonly IReadOnlyList<ScreenDefinition> Screens =
+    [
+        new("dashboard", "Dashboard", "/"),
+        new("projects", "Projects", "/projects"),
+        new("tasks", "Tasks", "/tasks"),
+        new("documents", "Documents", "/documents"),
+        new("accounts", "Accounts", "/accounts"),
+        new("roles", "Roles", "/roles"),
+    ];
+
+    public static readonly IReadOnlySet<string> Keys = Screens.Select(s => s.Key).ToHashSet();
+}