feat: Enable Nix shell

Also add a script to automate this process by creating a JSON file based
on the current state of the relevant channel
<https://github.com/linz/geostore/pull/2130/files>.

.gitignore

@@ -2,5 +2,5 @@ ACTIVATION
 .authcode
 *aax
 *jpg
-*json
+*-chapters.json
 Audiobook/*

bump-nixpkgs.bash

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+set -o errexit -o nounset -o pipefail
+shopt -s failglob inherit_errexit
+
+if [[ $# -ne 1 ]]; then
+    cat >&2 <<EOF
+bump-nixpkgs.bash: Update nixpkgs.json with latest info from given release
+
+Usage:
+
+./bump-nixpkgs.bash RELEASE
+
+Example:
+
+./bump-nixpkgs.bash 22.05
+    Bumps nixpkgs within the 22.05 release.
+EOF
+    exit 2
+fi
+
+release="$1"
+
+cleanup() {
+    rm --force --recursive "$working_dir"
+}
+trap cleanup EXIT
+working_dir="$(mktemp --directory)"
+
+intermediate_file="${working_dir}/1.json"
+full_file="${working_dir}/2.json"
+target_file=./nixpkgs.json
+curl "https://api.github.com/repos/NixOS/nixpkgs/git/refs/heads/release-${release}" |
+    jq '{name: (.ref | split("/")[-1] + "-" + (now|strflocaltime("%Y-%m-%dT%H-%M-%SZ"))), url: ("https://github.com/NixOS/nixpkgs/archive/" + .object.sha + ".tar.gz")}' >"$intermediate_file"
+jq '. + {sha256: $hash}' --arg hash "$(nix-prefetch-url --unpack "$(jq --raw-output .url "$intermediate_file")")" "$intermediate_file" >"$full_file"
+
+if diff <(jq 'del(.name)' "$full_file") <(jq 'del(.name)' "$target_file"); then
+    echo "No change; aborting." >&2
+else
+    mv "$full_file" "$target_file"
+fi

nixpkgs.json

@@ -0,0 +1,5 @@
+{
+  "name": "release-22.05-2022-10-16T19-25-26Z",
+  "url": "https://github.com/NixOS/nixpkgs/archive/945a85cb7ee31f5f8c49432d77b610b777662d4f.tar.gz",
+  "sha256": "0bvxw6lzi7n8vxr3dqcjmbypr8c7wzhz0flgmjlbswix8wmbyh0j"
+}

shell.nix

@@ -0,0 +1,25 @@
+let
+  pkgs =
+    import (
+      fetchTarball (
+        builtins.fromJSON (
+          builtins.readFile ./nixpkgs.json
+        )
+      )
+    ) {
+    };
+in
+  pkgs.mkShell {
+    packages = [
+      pkgs.alejandra
+      pkgs.bashInteractive
+      pkgs.cacert
+      pkgs.gitFull
+      pkgs.gitlint
+      pkgs.gnumake
+      pkgs.nix
+      pkgs.nixos-rebuild
+      pkgs.nodePackages.prettier
+      pkgs.pre-commit
+    ];
+  }