feat: add period tracker with calendar, predictions, fertility tracking, and sharing

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

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "homepage",
-	"version": "1.1.1",
+	"version": "1.2.0",
 	"private": true,
 	"type": "module",
 	"scripts": {