Add editor mode toggle fidelity guard

[Entr0zy]

Summary

• Adds a focused WYSIWYG/Markdown mode-toggle fidelity guard for issue Real-time collaborative research editor & interface #12.
• Detects equation token loss, citation key loss, notebook-cell link loss, comment anchor loss, tracked suggestion loss, and locked-block mutations introduced during live editor mode switching.
• Includes deterministic synthetic sample data plus JSON, Markdown, and SVG reviewer artifacts.

/claim #12

Validation

• node editor-mode-toggle-fidelity-guard/test.js
• node editor-mode-toggle-fidelity-guard/demo.js
• git diff --check

Demo artifacts

• editor-mode-toggle-fidelity-guard/reports/mode-toggle-packet.json
• editor-mode-toggle-fidelity-guard/reports/mode-toggle-report.md
• editor-mode-toggle-fidelity-guard/reports/summary.svg

Deconfliction

This checks losses introduced specifically at the WYSIWYG/Markdown live mode-switch boundary before collaborative edit acceptance. It is separate from broad round-trip export, accessibility parity, LaTeX macro safety, reference merge/formatting, equation or figure anchors, clipboard import, find/replace, chat mention scope, and journal-style guards.

Demo artifacts

• editor-mode-toggle-fidelity-guard/reports/demo.webm