add repo scaffold and the catalog-diff CLI

Compile a host's catalog in a base and a test environment over the
puppetserver API, then diff the two.

- add catalog-diff CLI with cobra flags, config precedence and exit codes
- add puppetserver mTLS client for POST /puppet/v4/catalog
- add pdbmux fact client
- add catalog normalisation, diff engine and text/JSON renderers
- add Makefile, nfpm RPM packaging and woodpecker pipelines

scripts/build-rpm.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+#
+# Package the (already built) puppet-catalog-tools binaries into an RPM with
+# nfpm, bundling generated bash/zsh/fish shell completions.
+# Usage: scripts/build-rpm.sh [version]   (version defaults to $CI_COMMIT_TAG)
+#
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "${ROOT_DIR}"
+
+VERSION="${1:-${CI_COMMIT_TAG:-0.0.0-dev}}"
+VERSION="${VERSION#v}" # strip a leading v
+PACKAGE="puppet-catalog-tools"
+BINARIES=(catalog-diff)
+DIST="dist"
+
+for b in "${BINARIES[@]}"; do
+  if [ ! -f "${DIST}/${b}" ]; then
+    echo "ERROR: ${DIST}/${b} not found; run 'make build' first" >&2
+    exit 1
+  fi
+done
+
+# Generate shell completions from the freshly built binaries so they always
+# match the shipped flags/subcommands.
+COMP_DIR="${DIST}/completions"
+mkdir -p "${COMP_DIR}"
+for b in "${BINARIES[@]}"; do
+  "./${DIST}/${b}" completion bash >"${COMP_DIR}/${b}.bash"
+  "./${DIST}/${b}" completion zsh >"${COMP_DIR}/_${b}"
+  "./${DIST}/${b}" completion fish >"${COMP_DIR}/${b}.fish"
+done
+
+export PACKAGE_NAME="${PACKAGE}"
+export PACKAGE_VERSION="${VERSION}"
+export PACKAGE_RELEASE="1"
+export PACKAGE_ARCH="amd64"
+export PACKAGE_PLATFORM="linux"
+export PACKAGE_DESCRIPTION="Puppet catalog tooling: catalog-diff compiles a host's catalog in two environments and diffs them"
+export PACKAGE_MAINTAINER="Ben Vincent <ben@unkin.net>"
+export PACKAGE_HOMEPAGE="https://git.unkin.net/unkin/puppet-catalog-tools"
+export PACKAGE_LICENSE="MIT"
+
+envsubst <packaging/nfpm.yaml >"${DIST}/nfpm.yaml"
+nfpm pkg --config "${DIST}/nfpm.yaml" --target "${DIST}" --packager rpm
+
+echo "Built:"
+ls -1 "${DIST}"/*.rpm