chore: remove unused reactjs-tiptap-editor dependency

This package was not imported anywhere in the codebase but pulled in
@excalidraw/excalidraw and old @radix-ui packages that caused peer
dependency warnings on every npm install (React 19 vs React 16-18).
Tiptap is used directly via @tiptap/* packages.

package.json

@@ -65,7 +65,6 @@
     "react-i18next": "^16.5.4",
     "react-router": "^7.13.0",
     "react-twemoji": "^0.7.2",
-    "reactjs-tiptap-editor": "^1.0.19",
     "recharts": "^3.7.0",
     "sigma": "^3.0.2",
     "simplex-noise": "^4.0.3",