refactor: restructure extensions

packages/extension-text/src/text.ts

@@ -0,0 +1,14 @@
+import { Node } from '@tiptap/core'
+
+const Text = Node.create({
+  name: 'text',
+  group: 'inline',
+})
+
+export default Text
+
+declare module '@tiptap/core' {
+  interface AllExtensions {
+    Text: typeof Text,
+  }
+}