marsyuri/KlangIT_V3 — reverse-engineered prompt

Build out this KlangIT V3 project into a working C# ASP.NET Core web app. The README doesn’t explain the product, so please inspect the existing folders, models, controllers, migrations, views, and services first, then continue the app in the same style instead of starting over.

I want a clean database backed site where a user can open it in the browser, see useful pages, work with the records already defined in the app, add and update them through simple forms, get clear validation messages, and navigate without hitting broken pages. Make the pages look tidy with the existing wwwroot assets, keep the code organized in the current MVC pattern, and make sure development settings, database migrations, and startup configuration all work.

If something is missing, make a sensible simple version and leave the code easy to understand. Look up current ASP.NET Core docs online if you need to.