feat: context sync diff/changelog between runs

[4444J99]

Description

organvm context sync currently broadcasts state into ~128 repos with no record of what changed between syncs. There is no diff, no changelog, and no rollback mechanism.

Proposed

• On each sync, compute diff between old and new auto-generated sections
• Write a context-sync-changelog.jsonl (append-only) with per-file change records
• Add organvm context diff [--last N] to review recent changes
• Consider organvm context rollback --to <timestamp> for emergency recovery

Priority

P2 — the system works without this, but debugging sync-related issues requires manual git archaeology across 128 repos.

Source

Documentation handoff architecture audit (2026-04-03).

[4444J99]

Backlog engagement 2026-07-19 — disposition: evolving.

Verified current main: context sync now returns per-file change records as changes/changelog and supports --diff output, with hashes and unified diff construction in src/organvm_engine/contextmd/sync.py. The full ask is only partial: I do not see an append-only context-sync-changelog.jsonl or rollback command on main. PR #105/#136 carry related work but are not merge-ready as-is.