fix: rename middleware to proxy for Next.js 16 compatibility

src/middleware.ts

@@ -1,35 +0,0 @@
-import { NextResponse } from "next/server";
-import type { NextRequest } from "next/server";
-
-export function middleware(request: NextRequest) {
-  const response = NextResponse.next();
-
-  const url = request.nextUrl.pathname;
-
-  if (
-    url.startsWith("/sr") ||
-    url.startsWith("/en") ||
-    url.startsWith("/de") ||
-    url.startsWith("/fr") ||
-    url === "/"
-  ) {
-    if (
-      !url.includes("/checkout") &&
-      !url.includes("/cart") &&
-      !url.includes("/api/")
-    ) {
-      response.headers.set(
-        "Cache-Control",
-        "public, max-age=3600, stale-while-revalidate=86400"
-      );
-    }
-  }
-
-  return response;
-}
-
-export const config = {
-  matcher: [
-    "/((?!_next/static|_next/image|favicon.ico|icon.png|robots.txt|sitemap.xml).*)",
-  ],
-};