feat(settings): Preferences show-comment-marker toggle

Closes out the Display subsection.

Outpost/Features/Account/SettingsView.swift

@@ -263,6 +263,13 @@ struct SettingsView: View {
                     isOn: session.userPreferences?.codeBlockLineNumbers ?? false,
                     onChange: { newValue in Task { await savePreference { $0.codeBlockLineNumbers = newValue } } }
                 )
+                Divider()
+                preferenceToggleRow(
+                    "Show comment marker",
+                    description: "Display a marker beside lines in the editor that contain comments.",
+                    isOn: session.userPreferences?.showCommentMarker ?? false,
+                    onChange: { newValue in Task { await savePreference { $0.showCommentMarker = newValue } } }
+                )
             }
 
             if let preferencesErrorMessage {