Fix Ruff formatting check for Markdown examples

[FLABDUL]

Summary

• apply Ruff 0.16.8 formatting to Python snippets embedded in Markdown
• keep the change limited to the three files reported by CI
• leave runtime code and behaviour unchanged

Root cause

The workflow accepts Ruff >=0.12.8 and installed Ruff 0.16.8, while the local environment used Ruff 0.15.8. The newer formatter checks these Markdown snippets differently.

Verification

• uvx --from ruff==0.16.8 ruff check .
• uvx --from ruff==0.16.8 ruff format --check .
• .venv/Scripts/pyrefly.exe check
• .venv/Scripts/python.exe -m pytest -q -o log_cli=false (424 passed, 3 skipped, 12 deselected)