fix(analysis): pad comparison chart Y domain to 20% around the range

apps/frontend/src/features/analysis/AnalysisPage.tsx

@@ -130,6 +130,24 @@ export function AnalysisPage({ currency }: { currency: string }) {
       .map(({ date, ...rest }) => ({ date: formatShortDate(date), ...rest }));
   }, [beloDaily, blueDaily, bnaDaily]);
 
+  const comparisonDomain = useMemo(() => {
+    if (comparisonData.length === 0) return [0, 0] as [number, number];
+    let min = Infinity;
+    let max = -Infinity;
+    for (const d of comparisonData) {
+      for (const key of ["BELO", "BLUE", "BNA"] as const) {
+        const value = d[key];
+        if (value === undefined) continue;
+        if (value < min) min = value;
+        if (value > max) max = value;
+      }
+    }
+    if (!Number.isFinite(min) || !Number.isFinite(max))
+      return [0, 0] as [number, number];
+    const range = max - min;
+    return [min - range * 0.2, max + range * 0.2] as [number, number];
+  }, [comparisonData]);
+
   const { yDomain, minBuyValue, maxBuyValue, avgBuyValue } = useMemo(() => {
     if (chartData.length === 0)
       return {
@@ -480,6 +498,7 @@ export function AnalysisPage({ currency }: { currency: string }) {
                       `$${priceFormatter.format(v)}`
                     }
                     width={80}
+                    domain={comparisonDomain}
                   />
                   <Tooltip
                     formatter={(value: unknown, name: unknown) => [