Add tarball script for CI

Allows the same script to be executed by GitLab and Gitea runners.

ci/make-tarball.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+set -e
+
+nix build -L '.#nixosConfigurations.lagarto-ox.pkgs.fpga-tarball'
+
+cd result
+out=/ceph/home/gitlab-runner/public_html/nixos-riscv/
+fn=$(ls | head -1)
+cp "$fn" "$out/$fn"
+rm -f "$out/latest.tar.zst"
+ln -s "$out/$fn" "$out/latest.tar.zst"
+rm result
+
+echo "Pinned: https://jungle.bsc.es/~gitlab-runner/nixos-riscv/$fn"
+echo "Latest: https://jungle.bsc.es/~gitlab-runner/nixos-riscv/latest.tar.zst"