feat: redesign day picker with expandable calendar, status markers & Playwright E2E testing

- Replace modal calendar with inline expandable calendar widget integrated into the day picker.
- Add status indicator dots (attended/absent/pending) to month calendar grid matching day picker.
- Disable and gray out weekend days in calendar when weekend schedule is turned off.
- Redesign extend bar with integrated handle that aligns with the palette.
- Remove start-to-end timing on Today screen's class time rail, showing only start time.
- Implement Playwright E2E and visual testing suite with multi-screen capture scripts.
- Add cascade DELETE endpoints for subjects and versioned recurring timetable entries.

components/ui/inline-banner.tsx

@@ -28,7 +28,7 @@ export function InlineBanner({ title, message, tone = 'neutral', action, style }
 }
 
 const styles = StyleSheet.create({
-  banner: { flexDirection: 'row', alignItems: 'flex-start', gap: spacing[3], borderRadius: radius.card, padding: spacing[4] },
+  banner: { flexDirection: 'row', alignItems: 'flex-start', gap: spacing[3], borderRadius: radius.card, borderCurve: 'continuous', padding: spacing[4] },
   copy: { flex: 1 },
   message: { marginTop: spacing[1] },
   action: { alignSelf: 'center' },