Add section lock autosave auditor

[Davidrsdiaz]

/claim #12

Summary

• add a deterministic section lock/autosave auditor for the real-time collaborative research editor
• detect non-owner edits inside hard-locked sections, expired lock leases, unauthorized unlocks, cursor presence in locked regions, offline lock conflicts, autosave gaps, missing version parents, restore overwrite risks, and named-version dirty-state issues
• include synthetic JSON, Markdown, SVG, and short MP4 demo artifacts

Tests

• node collaborative-research-editor/section-lock-autosave-auditor/test.js
• node collaborative-research-editor/section-lock-autosave-auditor/demo.js
• node collaborative-research-editor/section-lock-autosave-auditor/make-demo-video.js

All fixtures are synthetic and the module performs no private document, account, credential, notebook, kernel, or external API access.