Add alinea to server-external-packages.json (#55006)

### What?

Adds `@alinea/generated` to the external package list

### Why?

[`Alinea`](https://github.com/alineacms/alinea) generates this package
at build time and it should not end up in a cache (much like the
`@prisma/client` package)

---------

Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Tim Neutkens <tim@timneutkens.nl>

Author: 3 people

docs/01-app/03-api-reference/05-config/01-next-config-js/serverExternalPackages.mdx

@@ -18,6 +18,7 @@ module.exports = nextConfig
 
 Next.js includes a [short list of popular packages](https://github.com/vercel/next.js/blob/canary/packages/next/src/lib/server-external-packages.jsonc) that currently are working on compatibility and automatically opt-ed out:
 
+- `@alinea/generated`
 - `@appsignal/nodejs`
 - `@aws-sdk/client-s3`
 - `@aws-sdk/s3-presigned-post`

docs/02-pages/04-api-reference/04-config/01-next-config-js/serverExternalPackages.mdx

@@ -18,6 +18,7 @@ module.exports = nextConfig
 
 Next.js includes a [short list of popular packages](https://github.com/vercel/next.js/blob/canary/packages/next/src/lib/server-external-packages.jsonc) that currently are working on compatibility and automatically opt-ed out:
 
+- `@alinea/generated`
 - `@appsignal/nodejs`
 - `@aws-sdk/client-s3`
 - `@aws-sdk/s3-presigned-post`

packages/next/src/lib/server-external-packages.jsonc

@@ -1,4 +1,6 @@
 [
+  // alineacms.com generates this package at build time and it should not end up in a cache (much like the @prisma/client package)
+  "@alinea/generated",
   "@appsignal/nodejs",
   "@aws-sdk/client-s3",
   "@aws-sdk/s3-presigned-post",