Remove legacy files and update examples to use dist imports

Co-authored-by: kalwalt <[email protected]>

Author: Copilot

examples/basic-ecs/image-example.html

@@ -95,8 +95,7 @@
     </div>
 
     <script type="module">
-      import { Engine } from '../../src/core/engine.js';
-      import { imagePlugin } from '../../plugins/source/image.js';
+      import { Engine, imagePlugin } from '../../dist/arjs-core.mjs';
 
       const statusEl = document.getElementById('status');
       const urlEl = document.getElementById('url');