feat: add perp bench cards to alternatives pages for perp venues

src/app/alternatives/[slug]/page.tsx

@@ -20,6 +20,10 @@ import { citableAsOf } from "@/lib/citation";
 import { ProviderLogo } from "@/components/provider-logo";
 import { ProviderTypeBadge } from "@/components/provider-type-badge";
 import { isRegion } from "@/lib/brand";
+import { PERP_VENUE_META, benchRowsForVenue } from "@/lib/perp-venue-context";
+import { fetchPerpCohort } from "@/lib/perp-stats";
+import { loadBenchFromBlob } from "@/lib/bench-blob";
+import { PerpVenueBenchCards } from "@/components/perp-venue-bench-cards";
 
 export const revalidate = 60;
 
@@ -63,9 +67,21 @@ export default async function AlternativePage({
   params: Promise<Params>;
 }) {
   const { slug } = await params;
-  const alt = await loadAlternative(slug);
+  const isPerpVenue = slug in PERP_VENUE_META;
+
+  const [alt, cohort, feesAtSizeBench] = await Promise.all([
+    loadAlternative(slug),
+    isPerpVenue ? fetchPerpCohort() : Promise.resolve(null),
+    isPerpVenue ? loadBenchFromBlob("perp-fees-at-size") : Promise.resolve(null),
+  ]);
   if (!alt) notFound();
 
+  const venueRow = cohort?.venues.find((v) => v.slug === slug) ?? null;
+  const perpBenchRows =
+    cohort && venueRow
+      ? benchRowsForVenue(cohort, venueRow, feesAtSizeBench)
+      : [];
+
   const { bench } = alt;
   const isDraft = bench.status === "draft";
   const { fieldMin, fieldMedian, fieldMax, tailMin, tailMax, tailSpread } =
@@ -244,6 +260,15 @@ export default async function AlternativePage({
         </p>
       )}
 
+      {perpBenchRows.length > 0 && (
+        <section className="mt-10">
+          <SectionLabel>{alt.target_product} across benchmarks</SectionLabel>
+          <div className="mt-4">
+            <PerpVenueBenchCards rows={perpBenchRows} />
+          </div>
+        </section>
+      )}
+
       {/* Top alternatives cards - explicit list with internal links to
           product pages. The bench leaderboard below carries the full data;
           this section frames the answer for skim-readers and search. */}