fix: adapt to StarterKit v3 API changes

StarterKit v3 now includes Link, Underline, and UndoRedo by default.
- Remove separate Link import/config, use StarterKit's link option
- Disable undoRedo in StarterKit (replaced by CollaborationUndo)
- Apply same fix to backend publisher extensions

Made-with: Cursor

backend/src/publisher/extensions.ts

@@ -10,7 +10,6 @@
 import { Node, mergeAttributes, type Extensions } from "@tiptap/core";
 import StarterKit from "@tiptap/starter-kit";
 import CodeBlockLowlight from "@tiptap/extension-code-block-lowlight";
-import Link from "@tiptap/extension-link";
 import Mathematics from "@tiptap/extension-mathematics";
 import Image from "@tiptap/extension-image";
 import { Table } from "@tiptap/extension-table";
@@ -306,9 +305,9 @@ export function getServerExtensions(): Extensions {
   return [
     StarterKit.configure({
       codeBlock: false,
+      link: { openOnClick: false },
     } as any),
     CodeBlockLowlight.configure({ lowlight }),
-    Link.configure({ openOnClick: false }),
     Mathematics.configure({ katexOptions: { throwOnError: false } }),
     Image.configure({ allowBase64: true }),
     Table.configure({ resizable: false }),

frontend/src/editor/Editor.tsx

@@ -5,7 +5,7 @@ import Collaboration from "@tiptap/extension-collaboration";
 import CollaborationCursor from "@tiptap/extension-collaboration-cursor";
 import Placeholder from "@tiptap/extension-placeholder";
 import CodeBlockLowlight from "@tiptap/extension-code-block-lowlight";
-import Link from "@tiptap/extension-link";
+// Link is included in StarterKit v3, configured via StarterKit options
 import Mathematics from "@tiptap/extension-mathematics";
 import "katex/dist/katex.min.css";
 import { all, createLowlight } from "lowlight";
@@ -149,17 +149,17 @@ export function Editor({
       },
       extensions: [
         StarterKit.configure({
-          history: false,
           codeBlock: false,
-        }),
+          undoRedo: false,
+          link: {
+            openOnClick: false,
+            HTMLAttributes: { class: "editor-link" },
+          },
+        } as any),
         CodeBlockLowlight.configure({ lowlight }),
         Placeholder.configure({
           placeholder: 'Type "/" for commands...',
         }),
-        Link.configure({
-          openOnClick: false,
-          HTMLAttributes: { class: "editor-link" },
-        }),
         Collaboration.configure({
           document: ydoc,
         }),