fix(editor): disable StarterKit Link to prevent duplicate extension warning

StarterKit v3.x now includes the Link extension by default. The codebase
separately adds Link.configure() with custom settings (openOnClick: false,
custom HTMLAttributes). This caused the Tiptap warning:
"Duplicate extension names found: ['link']"

Disable StarterKit's built-in Link so the custom-configured one is used.

Made-with: Cursor

apps/x/apps/renderer/src/components/markdown-editor.tsx

@@ -311,6 +311,7 @@ export function MarkdownEditor({
         heading: {
           levels: [1, 2, 3],
         },
+        link: false, // Disable StarterKit's Link to use custom-configured one below
       }),
       Link.configure({
         openOnClick: false,