Selective workflow rollback needs separate history and decision compatibility

Observed 2026-09-07 during e3-solutions/theft COR-4076 (PR #804), comparing PR #722 with its parent. Removing an episode-based review workflow while retaining its queue/history UI requires two distinct compatibility contracts: immutable past decisions must remain readable, while old pending state must stop controlling future automation. Merely restoring the old writer can make already-settled decisions disappear from recomputation; blindly reading all newer-format history can resurrect an obsolete acceptance after another bypass. Preserve settled decisions at the legacy reader, recognize an explicit reset, and build History from audits plus both JSON formats with deduplication. Separately, status-projection changes require version invalidation and a correct fallback before the backfill. This is an implementation-derived rollback lesson, not a production validation claim. Provenance: historical code diff and focused compatibility tests in https://github.com/e3-solutions/theft/pull/804; full database integration remains unverified locally due older schema.