feat(routing): /sf -> /site-finder permanent redirect (short URL alias)

frontend/next.config.ts

@@ -22,6 +22,17 @@ const nextConfig: NextConfig = {
       { source: "/health", destination: `${backend}/health` },
     ];
   },
+  // /sf — короткий алиас для /site-finder (legacy short URL).
+  async redirects() {
+    return [
+      { source: "/sf", destination: "/site-finder", permanent: true },
+      {
+        source: "/sf/:path*",
+        destination: "/site-finder/:path*",
+        permanent: true,
+      },
+    ];
+  },
 };
 
 export default nextConfig;