Fix Cesium globe transparency in iSamples Explorer

- Use correct Cesium Ion token (matching other tutorials)
- Simplify viewer options to match working parquet_cesium_isamples_wide.qmd

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: rdhyee

tutorials/isamples_explorer.qmd

@@ -214,18 +214,14 @@ viewer = {
     }
   });
 
-  Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiI1YjQzMzgxNC00Y2M4LTRjZjktOTgzYS04MWI4YjE5OWNmMzciLCJpZCI6MjY1MTM4LCJpYXQiOjE3MzQ3MzI2MDZ9.O4SQmImLB7L98J65G_N-Kx2LGrv8_WQnfbGPCd8qjF0';
+  Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiIwNzk3NjkyMy1iNGI1LTRkN2UtODRiMy04OTYwYWE0N2M3ZTkiLCJpZCI6Njk1MTcsImlhdCI6MTYzMzU0MTQ3N30.e70dpNzOCDRLDGxRguQCC-tRzGzA-23Xgno5lNgCeB4';
 
   const container = document.getElementById('cesiumContainer');
 
   const v = new Cesium.Viewer(container, {
     timeline: false,
     animation: false,
     baseLayerPicker: false,
-    geocoder: false,
-    homeButton: true,
-    sceneModePicker: false,
-    navigationHelpButton: false,
     fullscreenElement: container,
     terrain: Cesium.Terrain.fromWorldTerrain()
   });