chore: synchronising ci/cd, linting, nix, scripts

.env.example

@@ -0,0 +1,20 @@
+# Unused atm (jest sets this to `test`)
+NODE_ENV=development
+
+# Debug node modules - https://nodejs.org/api/cli.html#node_debugmodule
+# NODE_DEBUG=
+
+# Debug node native modules - https://nodejs.org/api/cli.html#node_debug_nativemodule
+# NODE_DEBUG_NATIVE=
+
+# Path to container registry authentication file used by `skopeo`
+# The file has the same contents as `DOCKER_AUTH_CONFIG`
+# Use this command to acquire the auth file at `./tmp/auth.json`:
+# ```
+# printf 'PASSWORD' | skopeo login \
+#   --username 'USERNAME' \
+#   --password-stdin \
+#   $CI_REGISTRY_IMAGE \
+#   --authfile=./tmp/auth.json
+# ```
+# REGISTRY_AUTH_FILE=