web: bump Next.js to 14.0 for faster local server startup (#1925)

web/app/layout.tsx

@@ -1,3 +1,4 @@
+import type { Viewport } from 'next'
 import I18nServer from './components/i18n-server'
 import BrowerInitor from './components/browser-initor'
 import SentryInitor from './components/sentry-initor'
@@ -8,7 +9,14 @@ import './styles/markdown.scss'
 
 export const metadata = {
   title: 'Dify',
-  viewport: 'width=device-width, initial-scale=1, maximum-scale=1, viewport-fit=cover, user-scalable=no',
+}
+
+export const viewport: Viewport = {
+  width: 'device-width',
+  initialScale: 1,
+  maximumScale: 1,
+  viewportFit: 'cover',
+  userScalable: false,
 }
 
 const LocaleLayout = ({