Added:
- Interval mode: create timed work/rest cycles with customizable rounds
- Calendar view tab for browsing records
- Programs and intervals in ToDo list
- Day-of-week repeat for ToDo tasks
- Exercise description field (max 60 chars)
- Swipe navigation between record view tabs
- Interval and ToDo data in JSON backup (v7/v8)

Improved:
- Calendar period filter: gray out out-of-range dates, show all records
- Various UI refinements (toggle buttons, timer layout, etc.)

Fixed:
- Long-press on drag handle triggering repeat dialog

Contributors: SomeTr
