change middleware to proxy to match conventions

proxy.ts

@@ -0,0 +1,12 @@
+import { NextResponse } from "next/server";
+import type { NextRequest } from "next/server";
+
+export function proxy(request: NextRequest) {
+    if (request.nextUrl.pathname === '/') {
+        return NextResponse.redirect(new URL('/fr', request.url));
+    }
+}
+
+export const config = {
+    matcher: '/',
+}