Add collaborative undo redo guard

[Davidrsdiaz]

/claim #12

Summary

• Adds a self-contained collaborative undo/redo provenance guard for issue Real-time collaborative research editor & interface #12.
• Validates inverse operations before shared manuscript mutation by checking operation ownership, stale section versions, intervening range conflicts, locked final-review sections, notebook output restore snapshots, protected reviewer comment anchors, redo provenance, and deterministic allow/defer/block audit actions.
• Generates deterministic JSON, Markdown, SVG, and H.264 MP4 reviewer artifacts from synthetic data only.

Demo

• collab-undo-redo-provenance-guard/reports/demo.mp4
• collab-undo-redo-provenance-guard/reports/undo-redo-provenance-summary.svg

Validation

• node collab-undo-redo-provenance-guard/test.js
• node collab-undo-redo-provenance-guard/demo.js
• node collab-undo-redo-provenance-guard/make-demo-video.js
• node --check collab-undo-redo-provenance-guard/index.js
• node --check collab-undo-redo-provenance-guard/sample-data.js
• node --check collab-undo-redo-provenance-guard/demo.js
• node --check collab-undo-redo-provenance-guard/test.js
• node --check collab-undo-redo-provenance-guard/make-demo-video.js
• ffprobe -v error -select_streams v:0 -show_entries stream=codec_name,width,height,duration,nb_frames -show_entries format=size,duration -of default=noprint_wrappers=1 collab-undo-redo-provenance-guard/reports/demo.mp4 -> H.264, 1280x720, 4.0s, 48 frames
• git diff --check
• git diff --cached --check

Safety

Synthetic fixtures only. No live editor, notebook kernel, storage service, private manuscript data, credentials, or external service calls are used.