fix(learn): an editor with nobody signed in above it checks nothing

The full window editor is also shown without a person's scope, as a
privacy test pumps it, where GrammarHost asserted for want of one.
halkyon_app's PersonScope gains maybeOf beside of.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_flutter/lib/src/core/dependencies/person_dependencies.dart

@@ -132,6 +132,10 @@ class PersonDependencies({
   static PersonDependencies of(BuildContext context) =>
       PersonScope.of<PersonDependencies>(context);
 
+  /// As [of], or null where nobody is signed in above [context].
+  static PersonDependencies? maybeOf(BuildContext context) =>
+      PersonScope.maybeOf<PersonDependencies>(context);
+
   /// Closes what was opened for the person.
   @override
   Future<void> dispose() async {

apps/learn/halkyon_learn_flutter/lib/src/core/editor/rich_content_editor.dart

@@ -5,6 +5,7 @@ import 'package:appflowy_editor/appflowy_editor.dart';
 import 'package:flutter/foundation.dart';
 import 'package:halkyon_learn_flutter/l10n/app_localizations.dart';
 import 'package:halkyon_learn_flutter/src/core/content/rich_content.dart';
+import 'package:halkyon_learn_flutter/src/core/dependencies/person_dependencies.dart';
 import 'package:halkyon_learn_flutter/src/core/editor/block_menu.dart';
 import 'package:halkyon_learn_flutter/src/core/editor/core_blocks.dart';
 import 'package:halkyon_learn_flutter/src/core/editor/editor_blocks.dart';
@@ -194,13 +195,15 @@ class _RichContentEditorState() extends State<RichContentEditor> {
       ),
     );
     final checked = switch (widget.grammar) {
-      final language? => GrammarHost(
-        editorState: _editorState,
-        focusNode: _focus,
-        language: language,
-        child: appFlowyEditor,
-      ),
-      null => appFlowyEditor,
+      // Checked for the person signed in; nobody is outside their app.
+      final language? when PersonDependencies.maybeOf(context) != null =>
+        GrammarHost(
+          editorState: _editorState,
+          focusNode: _focus,
+          language: language,
+          child: appFlowyEditor,
+        ),
+      _ => appFlowyEditor,
     };
     final editor = switch (defaultTargetPlatform) {
       TargetPlatform.android || TargetPlatform.iOS => MobileFloatingToolbar(