Fix clock persistence bug caused by stale legacy read in settings
deserialization. Add clock size setting (Small/Medium/Large) and
timezone selection with North American presets plus custom UTC offset.
Move all clock-related settings into a dedicated Clock tab, rename
"Home Screen Clock" to "Clock", and move minute-change detection to
main loop so the header clock updates on every screen.
Co-authored-by: Cursor <cursoragent@cursor.com>
966fbef3d1
