fix(nix) fixed legacy xorg syntax

[pimkoter]

Built completed on nixpkgs rev 753cc8a3a87467296ddd1fa93f0cc3e81120ee46

[adibhanna]

Thanks a lot for digging into the Nix packaging, @pimkoter — and especially for the services.zennotes NixOS module, that's a genuinely useful addition. 🙏

I'm going to close this PR as-is, but I'd love to take part of it. Here's the reasoning, channel by channel:

• xorg.libX11 → libX11 (the titled "fix"): we just cut 2.15.0, and the nix-update workflow ran nix build .#zennotes-desktop .#zennotes-server on a Nix runner against current main — with the existing xorg.* syntax — and it built cleanly. So the desktop/server packages already build fine as-is; this change isn't fixing a break on our side.
• release-data.json hash: main is now at 2.15.0 with freshly recomputed, build-verified hashes, so the 2.14.0 line this PR edits is no longer used. (It also differed from the value our recompute step produced.)
• Formatting: the alejandra reformat of flake.nix / package-desktop.nix is a big diff that we'd rather not fold in alongside functional changes — it makes future diffs noisy against the current style.

What I'd genuinely like to merge is the server-module.nix on its own. Could you open a small, focused PR with just that file (plus the nixosModules.server wiring in flake.nix)? I'll run it through CI and get it in for the next release, with credit to you.

Really appreciate the contribution — sorry to send you a second lap on the module, but a focused PR will sail through.