chore: add a justfile (#389)

Similar to other hugrverse projects

justfile

@@ -0,0 +1,37 @@
+# List the available commands
+help:
+    @just --list --justfile {{justfile()}}
+
+# Prepare the environment for development, installing all the dependencies and
+# setting up the pre-commit hooks.
+setup:
+    poetry install
+    [[ -n "${JUST_INHIBIT_GIT_HOOKS:-}" ]] || poetry run pre-commit install -t pre-commit
+
+# Run the pre-commit checks.
+check:
+    poetry run pre-commit run --all-files
+
+# Run all the tests.
+test:
+    poetry run pytest
+
+# Auto-fix all clippy warnings.
+fix:
+    poetry run ruff check --fix guppylang
+
+# Format the code.
+format:
+    poetry run ruff format guppylang
+
+# Generate a test coverage report.
+coverage:
+    poetry run pytest --cov=./ --cov-report=html
+
+# Load a shell with all the dependencies installed
+shell:
+    poetry shell
+
+
+build-py-docs:
+    cd hugr-py/docs && ./build.sh