v0.20.38

Added

• ICS-URL calendar subscriptions: any user can subscribe to external calendars via HTTPS or webcal:// URL
• Per-subscription visibility (private or shared with all family members), custom color, and manual sync trigger
• REST API: GET/POST /api/v1/calendar/subscriptions, PATCH/DELETE /api/v1/calendar/subscriptions/:id, POST /api/v1/calendar/subscriptions/:id/sync
• POST /api/v1/calendar/:id/reset endpoint to clear user_modified on ICS events, allowing the next sync to restore upstream data
• ICS visibility filter on GET /api/v1/calendar and /upcoming: private subscription events are hidden from other users
• ICS subscription management card in Settings → Kalender tab (below Apple Calendar): subscription list with color dot, visibility badge, last-sync timestamp; inline add form with URL, name, color picker, and shared toggle; sync and delete actions
• "Auf Original zurücksetzen" link in calendar event popup for user-modified ICS events
• user_modified = 1 is set automatically when any externally-sourced event (ICS, Google, Apple) is edited by the user
• ICS sync integrated into the periodic runSync() scheduler alongside Google and Apple Calendar
• All new UI strings in public/locales/de.json under settings.ics.* and calendar.ics.*