persist font size, add :fav/:sub/:content commands

- note_editor: persist font size to SharedPreferences on change and
  restore it on load
- note_list: add :fav (toggle favorites filter), :sub (toggle
  subdirectory search), :content (toggle file content search) commands
- texts: document new commands in help content

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/note_editor.dart

@@ -56,6 +56,7 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
     final prefs = await SharedPreferences.getInstance();
     setState(() {
       _autoSaveEnabled = prefs.getBool('auto_save_enabled') ?? false;
+      _fontSize = prefs.getDouble('font_size') ?? 16.0;
     });
   }
 
@@ -164,6 +165,7 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
     setState(() {
       _fontSize = newSize;
     });
+    SharedPreferences.getInstance().then((prefs) => prefs.setDouble('font_size', newSize));
   }
 
   @override

lib/note_list.dart

@@ -669,6 +669,16 @@ Happy note taking! ✨
       case ':intern':
         _toggleExternalEditor(false);
         break;
+      case ':fav':
+        setState(() { _showOnlyFavorites = !_showOnlyFavorites; });
+        _filterNotes();
+        break;
+      case ':sub':
+        _toggleIncludeSubdirectories(!_includeSubdirectories);
+        break;
+      case ':content':
+        _toggleIncludeFileContent(!_includeFileContent);
+        break;
       case ':emptytrash':
         _confirmEmptyTrash();
         break;

lib/texts.dart

@@ -74,13 +74,16 @@ Empty folders are automatically removed after the last file is deleted.
 Type a colon command in the search bar and press Enter:
 
 :help – Open this guide.
+:about – Open app information.
 :tags – Toggle tag visibility.
+:fav – Toggle favorites filter.
+:sub – Toggle subdirectory search.
+:content – Toggle file content search.
 :day – Switch to light theme.
 :night – Switch to dark theme.
 :extern – Toggle external editor.
 :intern – Toggle internal editor.
 :emptytrash – Permanently delete trashed notes.
-:about – Open app information.
 
 
 """;