feat: show current-cycle daily token peak

backend/internal/app/api.go

@@ -533,6 +533,7 @@ func (a *App) syncAccount(ctx context.Context, id int64) error {
 			_, _ = a.store.DB.Exec("INSERT INTO daily_usage(account_id,date,total_tokens,fetched_at) VALUES(?,?,?,?) ON CONFLICT(account_id,date) DO UPDATE SET total_tokens=excluded.total_tokens,fetched_at=excluded.fetched_at", id, x.StartDate, x.Tokens, d.FetchedAt)
 		}
 		d.CurrentCycle = currentTokenCycle(d.Limits, d.Usage, d.FetchedAt)
+		d.Summary.PeakDailyTokens = peakDailyTokensForCycle(d.CurrentCycle, d.Usage, d.FetchedAt)
 	}
 	resetDetected, e := a.storeLimitSnapshots(d)
 	if e != nil {
@@ -642,6 +643,29 @@ func currentTokenCycle(limits []LimitBucket, usage []UsagePoint, fetchedAt int64
 	}
 }
 
+func peakDailyTokensForCycle(cycle *TokenCycle, usage []UsagePoint, fetchedAt int64) *int64 {
+	if cycle == nil {
+		return nil
+	}
+	startDate := time.Unix(cycle.StartedAt, 0).UTC().Format("2006-01-02")
+	endDate := time.Unix(fetchedAt, 0).UTC().Format("2006-01-02")
+	var peak int64
+	found := false
+	for _, point := range usage {
+		if _, err := time.Parse("2006-01-02", point.Date); err != nil || point.Date < startDate || point.Date > endDate {
+			continue
+		}
+		if !found || point.TotalTokens > peak {
+			peak = point.TotalTokens
+			found = true
+		}
+	}
+	if !found {
+		return nil
+	}
+	return &peak
+}
+
 func betterTokenCycleLimit(candidate, current LimitBucket) bool {
 	if candidate.WindowDurationMinutes != current.WindowDurationMinutes {
 		return candidate.WindowDurationMinutes > current.WindowDurationMinutes