Full period tracking system for the fitness measure page:
- Period logging with start/end dates, edit/delete support
- EMA-based cycle and period length predictions (α=0.3, 12 future cycles)
- Calendar view with connected range strips, overflow days, today marker
- Fertility window, peak fertility, ovulation, and luteal phase visualization
- Period sharing between users with profile picture avatars
- Cycle/period stats with 95% CI below calendar
- Redesigned profile card as inline header metadata with Venus/Mars icons
- Collapsible weight and period history sections
- Full DE/EN i18n support
Wraps the web app in a Tauri Android shell that provides native GPS
via the geolocation plugin. Includes foreground service for background
tracking, live map display, GPS data storage in workout sessions,
and route visualization in workout history.
