feat(pkgs): add nix-modrinth-prefetch

pkgs/nix-modrinth-prefetch.nix

@@ -0,0 +1,13 @@
+{ runtimeShell, writeShellScriptBin, curl, jq, gnused }:
+writeShellScriptBin "nix-modrinth-prefetch" ''
+  input=$(${curl}/bin/curl --no-progress-meter https://api.modrinth.com/v2/version/$1)
+
+  if [[ $input == "" ]]; then
+    echo "Invalid version"
+    exit 1
+  fi
+
+  echo $input \
+  | ${jq}/bin/jq -c '.files | (.[] | select(.primary == true)) // .[0]  | {url: .url, sha512: .hashes.sha512}' \
+  | ${gnused}/bin/sed 's/{"url":"\(.\+\)","sha512":"\(.\+\)"}/fetchurl { url = "\1"; sha512 = "\2"; }/'
+''