refactor: backstage design review

refactor: improve empty state

refactor: review schedule design

- fit as many elements as possible
- expose cycle interval as an option
- stabilise rundown reference
- style tweaks

apps/client/src/translation/languages/en.ts

@@ -11,6 +11,7 @@ export const langEn = {
   'common.stage_timer': 'Stage Timer',
   'common.started_at': 'Started At',
   'common.time_now': 'Time now',
+  'common.no_data': 'No data',
   'countdown.ended': 'Event ended at',
   'countdown.running': 'Event running',
   'countdown.select_event': 'Select an event to follow',