chore(deps): upgrade to nextjs 16 (#2203)

* chore(deps): upgrade to nextjs 16

* upgraded fumadocs

* ensure vercel uses bun

* fix build

* fix bui;d

* remove redundant vercel.json

apps/docs/proxy.ts

@@ -0,0 +1,25 @@
+import { createI18nMiddleware } from 'fumadocs-core/i18n/middleware'
+import { isMarkdownPreferred, rewritePath } from 'fumadocs-core/negotiation'
+import { type NextFetchEvent, type NextRequest, NextResponse } from 'next/server'
+import { i18n } from '@/lib/i18n'
+
+const { rewrite: rewriteLLM } = rewritePath('/docs/*path', '/llms.mdx/*path')
+const i18nProxy = createI18nMiddleware(i18n)
+
+export default function proxy(request: NextRequest, event: NextFetchEvent) {
+  if (isMarkdownPreferred(request)) {
+    const result = rewriteLLM(request.nextUrl.pathname)
+
+    if (result) {
+      return NextResponse.rewrite(new URL(result, request.nextUrl))
+    }
+  }
+
+  return i18nProxy(request, event)
+}
+
+export const config = {
+  matcher: [
+    '/((?!api|_next/static|_next/image|favicon|static|robots.txt|sitemap.xml|llms.txt|llms-full.txt).*)',
+  ],
+}