Make uv-lock pre-commit hook smart about release branches by wrapping it
in a script that detects release branches and sets UV_EXTRA_INDEX_URL.
This allows the same pre-commit config to work locally and in CI without
special environment variable setup in workflows.
Changes:
- Add scripts/pre-commit-uv-lock.sh wrapper that detects release branches
- Move uv-lock from astral-sh/uv-pre-commit to local hook using wrapper
- Remove UV env var setup from pre-commit workflow (hook handles it)
- Regenerate uv.lock with test.pypi as extra index (not primary)
