Remove unused cytoscape-spread and split build into manual chunks

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -28,7 +28,6 @@
     "cytoscape-dagre": "^2.5.0",
     "cytoscape-fcose": "^2.2.0",
     "cytoscape-popper": "^4.0.1",
-    "cytoscape-spread": "^3.0.0",
     "decimal.js": "^10.6.0",
     "i18next": "^25.8.14",
     "i18next-browser-languagedetector": "^8.2.1",