fix(cpa): do not overwrite custom.scss file on update (payloadcms#10285)

No longer overwrite an existing `custom.scss` file if using
`create-payload-app` to update an existing project.

Fixes payloadcms#9983

packages/create-payload-app/src/lib/update-payload-in-project.ts

@@ -87,6 +87,7 @@ export async function updatePayloadInProject(
   copyRecursiveSync(
     templateSrcDir,
     path.resolve(projectDir, appDetails.isSrcDir ? 'src/app' : 'app', '(payload)'),
+    ['custom.scss$'], // Do not overwrite user's custom.scss
   )
 
   return { message: 'Payload updated successfully.', success: true }