feat(ci): 👷 add gitlab pipeline template and document local checks

Changes

• Created .gitlab-ci.yml blueprint in package-template encapsulating ruff (formatting and linting), mypy (static types), and pytest -v automation jobs.
• Combined ruff format and ruff check into a single lint_code job to optimize overhead on local laptop runners.
• Assured all pipeline jobs install environment dependencies gracefully via uv sync prior to running.
• Assigned pipeline default tags to target ETHZ GEG laptop runners strictly as documented in computing-guide.wiki.
• Explicitly appended .gitlab-ci.yml to the array of automatically tracked initialization files within hooks/post_gen_project.py.
• Updated the README.md template to explicitly document how developers can manually run these exact uv validation checks (tests, linting, formatting, and type checking) locally.
• includes !10 (merged) and some of !14 (merged)

TODO before merging

• create a package with uvx --from cookiecutter cookiecutter git@gitlab.ethz.ch:geg/templates/package-template.git -c ci/setup-gitlab-pipeline, making sure to follow all printed and linked instructions
  • chad
  • @jblaume