* feat: add custom sync start time scheduling
* Updated UI
* docs: add updated issue 240 UI screenshot
* fix: improve schedule UI with client-side next run calc and timezone handling
- Compute next scheduled run client-side via useMemo to avoid permanent
"Calculating..." state when server hasn't set nextRun yet
- Default to browser timezone when enabling syncing (not UTC)
- Show actual saved timezone in badge, use it consistently in all handlers
- Match time input background to select trigger in dark mode
- Add clock icon to time picker with hidden native indicator
