What

• Added Google-style Attributes: sections to UpdateOp, InsertOp, DestroyOp, and SetFrameOp docstrings in src/pythonnative/mutations.py.

Why

• Only CreateOp had an Attributes: section; its sibling ops lacked field documentation.
• On the rendered docs/api/mutations.md page, CreateOp had a formatted attributes table while the other four ops didn't. Adding these sections ensures consistent API reference docs and satisfies repository docstring conventions.

How (brief)

• Documented tag and changed_props on UpdateOp (noting None for removed props).
• Documented parent_tag, child_tag, and index on InsertOp (noting handler clamping).
• Documented tag on DestroyOp.
• Documented tag, x, y, width, and height on SetFrameOp.

Testing

• Ran uv run ruff check . (passed).
• Ran uv run --group docs mkdocs build --strict (passed; verified rendered attributes tables on the Mutation ops page).
• Ran ./scripts/check.sh (all CI checks passed).

Risks/Impact

• None. Docstrings-only change.

Docs/Follow-ups

• None.

Closes #61