fix: trade log Invalid Date and equity curve duplicate timestamp crash

- TradeLog: use created_at (from API) instead of timestamp for date display
- EquityCurve: deduplicate data by day before passing to lightweight-charts,
  preventing "data must be asc ordered by time" assertion failure when
  multiple snapshots exist on the same day

Made-with: Cursor

dashboard/src/components/EquityCurve.tsx

@@ -68,10 +68,14 @@ export function EquityCurve({ data, height = 300 }: EquityCurveProps) {
   useEffect(() => {
     if (!seriesRef.current || !data.length) return;
 
-    const chartData = data.map((point) => ({
-      time: point.timestamp.split('T')[0] as string,
-      value: point.value,
-    }));
+    const byDay = new Map<string, number>();
+    for (const point of data) {
+      const day = point.timestamp.split('T')[0];
+      byDay.set(day, point.value);
+    }
+    const chartData = Array.from(byDay.entries())
+      .sort(([a], [b]) => a.localeCompare(b))
+      .map(([time, value]) => ({ time, value }));
 
     seriesRef.current.setData(chartData as any);