Run repo-wide pre-commit cleanup

[Muhtasham]

Summary

• Fix current Ruff lint drift in BattleCode23 and Chess without changing arena behavior.
• Run the existing pre-commit hooks across the repo, keeping the resulting mechanical formatting / EOF cleanup.
• Pin the typos hook to a concrete release, allowlist the intentional mis variable name, fix one real typo, and add CI coverage for pre-commit run --all-files.

Verification

• uv run pre-commit run --all-files
• uv run ruff check .
• uv run ruff format . --check
• uv run pytest tests/arenas/test_battlecode23.py tests/arenas/test_chess.py
• uv run pytest -v --cov --cov-branch --cov-report=xml -n auto (185 passed)
• uv run mkdocs build
• git diff --check

Opened as draft intentionally so this can run CI and be reviewed separately from the arena PRs.