Fix AutoCAD WinForms Plugin

The project is an AutoCAD add-in built with a WinForms C# front-end and a small C++ layer. Two problem areas need immediate attention:

1. Build & reference hygiene
Duplicate namespaces are popping up during compilation and a handful of obsolete or circular references have crept into the solution. Cleaning this up so the project builds without warnings or runtime conflicts is the first priority.

2. User-interface stability
Inside AutoCAD, the WinForms palette shows visual glitches and becomes unresponsive in places. The unresponsiveness is tied to the current coding syntax that wires the events, rather than to specific buttons or menus. Fixing those event hooks and any painting logic that causes flicker will restore a smooth UI.

Deliverables (all must be met for sign-off):
• Compilable solution with no duplicate namespace warnings and only essential references.
• Repaired UI that runs inside AutoCAD with no visual glitches or frozen elements.
• Brief change log outlining which namespaces were merged or renamed, which references were removed or updated, and what UI fixes were applied.

The codebase is available in a Git repository; after you finish, I will test the new DLL against AutoCAD before releasing the milestone.