Implement plan 02 synthetic recovery procedure

Read first:

1. Entire approved plan from local planning checkout only when its HEAD equals a2557b2ad40e06e1e63eb655f286e6a78fe6bf0d; otherwise use pinned git show fallback below.
2. Audit evidence: /Users/amruth/orca/workspaces/reactive-resume/codex-audit-backend-01-06/.orchestration/revalidate-backend-01-06.md, plan 02 section.
3. Current worktree AGENTS.md, referenced issue/domain instructions, relevant ADRs, /Users/amruth/.codex/RTK.md.
4. /Users/amruth/.agents/skills/test-driven-development/SKILL.md, its writing-good-tests.md reference, /Users/amruth/.agents/skills/karpathy-guidelines/SKILL.md, and /Users/amruth/.agents/skills/documentation-writer/SKILL.md.

Portable plan fallback: fetch PR #3455 and use git show a2557b2ad40e06e1e63eb655f286e6a78fe6bf0d:plans/02-hosted-v4-account-recovery.md.

Implement only synthetic, non-networked recovery support. This is partial support for #3181, not production recovery; #2760 remains a separate diagnostic. Do not access private/production data, spawn subagents, touch coordinator ledger/other worktrees, merge, push, create PR, or mutate issues.

Required execution:

• Confirm clean worktree; fetch current origin/main; rename branch codex/issue-3181-recovery-procedure; verify exact base; run plan drift command; fetch live #3181/#2760 evidence; run root intent discovery.
• Modify only docs/self-hosting/migration.mdx, docs/guides/accessing-the-previous-version.mdx, and new tooling/recovery/compare-resume.ts plus tooling/recovery/compare-resume.test.ts. Stop if another file is truly required and report before broadening.
• TDD tooling strictly: write focused behavior test, run it and capture expected missing-feature failure, implement minimum, rerun green, then refactor. Tests must exercise real function and hand-derived outcomes/hashes; no tautological helpers or mock assertions.
• Tool accepts already-exported JSON/current resume-shaped data only; no database URL or writes. Produce deterministic dry-run manifest with synthetic IDs, source/target hashes, and outcome no-op, export-copy, or blocked. Cover identical, old-only/divergent, owner-unverified/mapping-missing, unavailable snapshot, invalid source/target JSON, determinism, and no input mutation. Use current schema/default exports through package public exports. Do not invent legacy fields or convert v4.
• Docs specify per-owner case record, source snapshot time, owner verification, target ID, content hash, proposed outcome, default private export, separate copy/no overwrite, hosted-vs-self-hosted authority, missing-source factual limit, and private delivery gate. Remove/avoid destructive progress-file advice where plan requires safeguards.
• Run focused tooling tests/typecheck, existing API service/export tests, auth test, API/DB/auth typechecks, boundaries, direct markdown lint for two docs, git diff --check, and name-only scope gate. Record any environment-gated skips exactly.
• Self-review every plan acceptance and STOP condition. Commit normal message. Leave branch local for independent review.

Report .orchestration/plan-02-implementation.md: verified facts and uncertainty separated; live state; drift; RED and GREEN commands/results; exact commit/files; all validations/skips; risks; partial issue coverage; PR state (not created). Final response: status, commit, one-line tests, report path, concerns; at most ten lines.