feat: added a custom start node

Defined a basic start node; it does not contain any further functionality but does provide a basis for implementing future custom nodes.

ref: N25B-114

src/main.tsx

@@ -2,7 +2,7 @@ import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
 import './index.css'
 import App from './App.tsx'
-import VisualProgrammingUI from "./VisualProgrammingUI/VisProgUI.tsx";
+import VisualProgrammingUI from "./visualProgrammingUI/VisProgUI.tsx";
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>