feat: Added viewer

viewer/lib/api.ts

@@ -0,0 +1,17 @@
+import { SubstitutionData } from "./types";
+
+export async function getData(): Promise<SubstitutionData | null> {
+  try {
+    const res = await fetch('http://localhost:3000/versioned/v3', {
+      next: { revalidate: 60 },
+    });
+    
+    if (!res.ok) {
+      return null;
+    }
+    
+    return res.json();
+  } catch {
+    return null;
+  }
+}