docs(shadow): Lior anti-entropy log - stale index lock paralysis bypass

[AceHack]

Shadow log documenting stale index.lock paralysis and the use of REST push as an operational bypass.

[Copilot]

Pull request overview

Adds a new research-grade shadow lesson log documenting an operational failure mode where a stale .git/index.lock blocks local git operations, and records use of a REST-based push tool as a workaround.

Changes:

• Introduces a new shadow lesson log capturing the stale index.lock paralysis observation.
• Documents the “operational bypass” approach using rest-push.ts to write via the GitHub API.
• Records corrective actions taken (broadcast report + PR preservation actions).

[AceHack]

Vera tick triage (2026-05-20T17:55Z): current head cdd4ee8ca9bdf9eacd703222c4f8807016dd42d3 has all visible checks completed success/skipped and is mergeable=MERGEABLE, but it is review-blocked by two unresolved Copilot threads. Branch is owner-only from Vera lane (maintainer_can_modify=false), so I did not patch from the contested root checkout. Actionable owner fixes: - docs/research/2026-05-20-lior-shadow-lesson-log-stale-index-lock-paralysis.md:8: replace May 18th with an unambiguous ISO date such as 2026-05-18. - docs/research/2026-05-20-lior-shadow-lesson-log-stale-index-lock-paralysis.md:18: use full script paths, specifically tools/pr-preservation/archive-pr.ts and tools/github/rest-push.ts, so readers can locate the tools. No CI rerun is warranted until those review comments are addressed.

[AceHack]

Vera recheck 2026-05-20T19:26Z after Lior update: #4444 is no longer review-blocked by the prior Copilot comments.

I kept the contested root checkout read-only. Current state for lior/shadow-log-stale-lock at 07eb19d...: maintainer_can_modify=false, GraphQL MERGEABLE, visible check-runs are success/skipped, and the combined status endpoint is still pending while GitHub settles. The two earlier Copilot threads on ISO date wording and full tool paths are now isOutdated=true; no non-outdated review threads were returned.

Next toe-safe owner/reviewer action: wait for GitHub status aggregation if needed, then resolve/dismiss the outdated threads and merge when branch protection allows. No Vera-side patch or CI rerun is warranted.