Repository navigation

ci: adopt centralized Ruff checks #9

Job	Run time
Python syntax (no execution)	24s
Validate GitHub automation / Validate Actions and gh-aw sources	24s
Lint (ruff) / Ruff	24s
Validate GitHub automation / Test checked-script and Python syntax action contracts	-1s
Exercise solutions (Python ${{ matrix.python-version }})	1s
Test (Python ${{ matrix.python-version }} / ${{ matrix.os }})	1s
	1m 13s