[static] ruff format is configured but not enforced in CI; 5 files have drifted

[tiankaima]

Problem

pyproject.toml configures [tool.ruff.format] (double quotes, spaces, LF), but .github/workflows/ruff.yml only runs ruff check — formatting is not enforced in CI. It has already drifted: ruff format --check . on current master (369fc1a) reports 5 files:

Would reformat: src/curriculum.py
Would reformat: src/sqlite_store.py
Would reformat: src/utils/jw.py
Would reformat: tests/test_sqlite_store.py
Would reformat: tests/test_young.py

Suggested fix

Add uv run ruff format --check . to ruff.yml (and format the 5 drifted files once).