backfillData() only refreshed system settings after a successful backfill,
leaving state.sentimentHistory/sentimentHistoryKey populated with the stale
pre-backfill cache, so an already-open sentiment cycle page kept showing the
old one-day history.
After a successful backfill, clear both cache fields and, when the sentiment
cycle view is active, force loadSentimentHistory(true) so the history renders
immediately. Add a frontend contract test covering the refresh path.
Co-authored-by: multica-agent <github@multica.ai>
