feat: add backstop js test #56

	name: Backstop test
	on:
	push:
	branches:
	- main
	pull_request:
	branches:
	- main

	permissions:
	contents: read

	env:
	NODE_VERSION: "25.2.1"
	PYTHON_VERSION: "3.13"
	DOC_PORT: 8000

	jobs:
	backstop-tests:
	name: Visual regression tests
	runs-on: ubuntu-latest
	steps:
	- name: Checkout repository
	uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
	with:
	persist-credentials: false

	- name: Set up Node
	uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903
	with:
	node-version: ${{ env.NODE_VERSION }}

	- name: Install uv
	uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
	with:
	python-version: ${{ env.PYTHON_VERSION }}

	- name: Install dependencies
	run: \|
	npm install

	- name: Install xvfb
	run: sudo apt-get install -y xvfb pandoc

	- name: Create virtual environment
	run: uv venv

	- name: Build documentation
	run: \|
	source .venv/bin/activate
	uv pip install --group doc .
	xvfb-run make -C doc html

	- name: Serve documentation
	run: npx http-server -u -p $env.DOC_PORT ./doc/_build/html &

	- name: check if server is up
	run: curl -I http://localhost:$env.DOC_PORT \|\| true

	- name: Run BackstopJS tests
	run: \|
	npm run test

	- name: Upload Backstop report (if failed)
	if: failure()
	uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
	with:
	name: backstop-report
	path: backstop_data/html_report

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