Add checkpoint save/load system #856

	name: Run tests and upload coverage
	on: [push, pull_request]
	jobs:
	test:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- name: Set up Python
	uses: actions/setup-python@v5
	with:
	python-version: '3.x'
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install -e .[test,rf]
	- name: Test with pytest and generate coverage
	run: \|
	pytest --cov=./src/pathsim --cov-report=xml
	- name: Upload coverage to Codecov
	uses: codecov/codecov-action@v5
	with:
	token: ${{ secrets.CODECOV_TOKEN }}
	slug: pathsim/pathsim
	fail_ci_if_error: true
	files: ./coverage.xml

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