A3S Office v0.83.0

Writer Phase 0 reviewable row grid-before property revisions.

Writer

• Reviewable row-formatting for gridBefore with accept/reject, live track-changes, and native DOCX export (including current-row write)
• Opaque row fixtures moved to gridAfter; broader tcPr / trPr shapes stay opaque or fail-closed

See CHANGELOG.md for the full engineering notes.