fix(i18n): align middleware with Cloudflare routing

Author: ericyangpan

src/middleware.ts

@@ -1,32 +1,10 @@
-import type { NextRequest } from 'next/server'
 import createMiddleware from 'next-intl/middleware'
-import { defaultLocale, locales } from './i18n/config'
+import { routing } from './i18n/routing'
 
-const intlMiddleware = createMiddleware({
-  // A list of all locales that are supported
-  locales,
-
-  // Used when no locale matches
-  defaultLocale,
-
-  // Don't prefix the default locale (English)
-  localePrefix: 'as-needed',
-
-  // Detect locale from Accept-Language header
-  localeDetection: true,
-})
-
-export default function middleware(request: NextRequest) {
-  // Check for stored locale preference
-  const localeCookie = request.cookies.get('NEXT_LOCALE')
-  if (localeCookie?.value) {
-    // Clone the request headers and add the locale preference
-    const requestHeaders = new Headers(request.headers)
-    requestHeaders.set('x-locale-preference', localeCookie.value)
-  }
-
-  return intlMiddleware(request)
-}
+// Next.js 16 Proxy always uses the Node.js runtime, which the current
+// @opennextjs/cloudflare adapter does not support for middleware yet.
+// Keep the legacy Edge Middleware convention until adapter support lands.
+export default createMiddleware(routing)
 
 export const config = {
   // Match only internationalized pathnames