CI: align workflows with python-proxy-headers and add release skill #1

	# When a release/* PR merges into main, create a GitHub release (tag vX.Y.Z).
	# Events from GITHUB_TOKEN do not start other workflows; push_gem.yml is triggered via
	# workflow_run when this workflow completes (see push_gem.yml).

	name: Release on merge

	on:
	pull_request:
	types: [closed]
	branches:
	- main

	concurrency:
	group: release-on-merge-${{ github.event.pull_request.number }}
	cancel-in-progress: false

	permissions:
	contents: write

	jobs:
	github-release:
	if: >-
	github.event.pull_request.merged == true &&
	startsWith(github.head_ref, 'release/') &&
	github.event.pull_request.head.repo.full_name == github.repository
	runs-on: ubuntu-latest
	steps:
	- name: Checkout merge commit
	uses: actions/checkout@v6
	with:
	ref: ${{ github.event.pull_request.merge_commit_sha }}

	- name: Read version from lib/ruby_proxy_headers/version.rb
	id: meta
	run: \|
	VERSION=$(ruby -r ./lib/ruby_proxy_headers/version.rb -e 'puts RubyProxyHeaders::VERSION')
	echo "version=${VERSION}" >> "${GITHUB_OUTPUT}"

	- name: Create GitHub Release
	env:
	GH_TOKEN: ${{ github.token }}
	run: \|
	set -euo pipefail
	VERSION="${{ steps.meta.outputs.version }}"
	TAG="v${VERSION}"
	MERGE_SHA="${{ github.event.pull_request.merge_commit_sha }}"
	if gh release view "${TAG}" --repo "${{ github.repository }}" >/dev/null 2>&1; then
	echo "Release ${TAG} already exists; skipping."
	exit 0
	fi
	gh release create "${TAG}" \
	--repo "${{ github.repository }}" \
	--target "${MERGE_SHA}" \
	--title "${TAG}" \
	--generate-notes

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