recordHistory() only ever stored fiveHourUtilization/weeklyUtilization, but
fetchUsage() returned early with message-count data — before calling the
/usage utilization endpoint — whenever the org JSON carried a message limit.
So utilization was never populated and the history chart stayed stuck on
'Collecting history…'. The prior chart fix only corrected the throttle.
- UsageRepository: always attempt /usage (preferred signal that drives the
weekly bar + history); fall back to org message-count data only when
utilization is unavailable.
- UsageData.sessionReadingPct: utilization preferred, message-count % fallback,
-1f when no reading — so message-only accounts also build history.
- PreferencesManager.recordHistory: record the session line from
sessionReadingPct instead of utilization-only.
- UsageDataTest: cover sessionReadingPct.