[BUG] Upgrade to Next.js v15.4.4 needed

[cording12]

Turbopack introduced an issue, specifically on Windows, around file paths in the monorepo, as described in #81628.

Vercel fixed this problem in 15.4.3, and stabilised better in 15.4.4, but as of right now OpenNext only supports Next.js up to version 15.3.

OpenNext is reviewing this in #667

[mohsentaleb]

Great work! Latest version in branch 15 is now 15.5.6. Are you still updating this repo?

[cording12]

@mohsentaleb I haven't had time to update just yet, but think this is solved in this OpenNext PR. I'll test when I have time and update if all appears OK.

You can bump the Next.js version yourself though, no need to wait for me as it might take a week or so

P.S. Yes to your question about updating - I'm working a separate CLI that will massively improve (IMO) the project as it'll become composable going forward, i.e. choose your auth, db, ORM etc.