Flexible List Strikethrough Controls

[greetclammy]

Describe the solution you'd like

1. In addition to "Strike completed tasks" toggle, add "Strike cancelled tasks" toggle.
2. For both "Strike completed tasks" and "Strike cancelled tasks":
   • Add toggle: "Apply to indented/child items"

Rationale: This allows to maintain visibility of notes related to completed or cancelled tasks, which may contain important information, while still visually distinguishing the status of parent tasks.