Add collaborative find replace safety guard

[Davidrsdiaz]

/claim #12

Summary

• Adds a distinct collaborative find/replace safety guard for the real-time research editor.
• Previews batch replacement operations before shared manuscript mutation and holds edits that touch locked/final-review sections, citation keys, LaTeX commands, notebook/code cells, cross-reference anchors, or inline comment quote anchors.
• Emits deterministic JSON, Markdown, SVG, and MP4 reviewer artifacts from synthetic data only.

Non-overlap

This is a batch edit preview/mutation guard. It is separate from broad editor foundations, operation replay, offline conflict, notebook/kernel lease, reference merge/formatting, authorship, freeze/recovery, discussion sidebar, autosave recovery, round-trip export fidelity, review decision, task dependency, presence/privacy, accessibility, evidence-binding, embargo, notification visibility, data availability, LaTeX macro safety, suggestion provenance, local-cache privacy, clipboard/import provenance, notebook output reproducibility, and comment-anchor drift slices.

Demo evidence

• collaborative-research-editor/find-replace-safety-guard/reports/demo.mp4
• collaborative-research-editor/find-replace-safety-guard/reports/find-replace-review.json
• collaborative-research-editor/find-replace-safety-guard/reports/find-replace-review.md
• collaborative-research-editor/find-replace-safety-guard/reports/find-replace-summary.svg

Validation

• node collaborative-research-editor/find-replace-safety-guard/test.js
• node collaborative-research-editor/find-replace-safety-guard/demo.js
• node collaborative-research-editor/find-replace-safety-guard/make-demo-video.js
• ffprobe verified reports/demo.mp4 as H.264, 1280x720, 4s, 12 fps
• node --check on module/demo/video scripts
• git diff --cached --check before commit

Synthetic data only. No credentials, private manuscript data, live editor state, external APIs, payment details, or unrelated changes are included.