v2.8.4

Fixed

• Preserve subtasks when spawning recurring task occurrences. Completing a recurring parent task with subtasks now copies its subtask structure with reset status (open) to the next occurrence, preserving checklists and multi-step workflows across occurrences (#742, #744). Undoing completion discards pristine spawned follow-up tasks while preserving any follow-up tasks whose subtasks were completed or edited.