Removed p wrapper for koenig-lexical-input (#16754)

refs TryGhost/Team#3147

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### <samp>🤖 Generated by Copilot at 7dfd8bf</samp>

This file adds a function to clean and format the HTML of the
`koenig-lexical-editor-input` component and passes it to the
`HtmlOutputPlugin` component.

ghost/admin/app/components/koenig-lexical-editor-input.js

@@ -1,6 +1,7 @@
 import * as Sentry from '@sentry/ember';
 import Component from '@glimmer/component';
 import React, {Suspense} from 'react';
+import cleanBasicHtml from '@tryghost/kg-clean-basic-html';
 import {action} from '@ember/object';
 import {inject} from 'ghost-admin/decorators/inject';
 import {inject as service} from '@ember/service';
@@ -117,7 +118,16 @@ export default class KoenigLexicalEditorInput extends Component {
         // don't rethrow, Lexical will attempt to gracefully recover
     }
 
-    ReactComponent = (props) => {
+    ReactComponent = (props = {}) => {
+        // remove `p` wrapper
+        const cleanHtml = (html) => {
+            const cleanedHtml = cleanBasicHtml(html || '', {firstChildInnerContent: true});
+            props.onChangeHtml?.(cleanedHtml);
+        };
+
+        // wrap in a paragraph, so it gets parsed correctly
+        const initialHtml = props.html ? `<p>${props.html}</p>` : null;
+
         return (
             <div className={['koenig-react-editor', this.args.className].filter(Boolean).join(' ')}>
                 <ErrorHandler>
@@ -136,7 +146,7 @@ export default class KoenigLexicalEditorInput extends Component {
                                 placeholderText={props.placeholderText}
                                 placeholderClassName="koenig-lexical-editor-input-placeholder"
                             >
-                                <HtmlOutputPlugin html={props.html} setHtml={props.onChangeHtml} />
+                                <HtmlOutputPlugin html={initialHtml} setHtml={cleanHtml} />
                             </KoenigComposableEditor>
                         </KoenigComposer>
                     </Suspense>