fix(tui): cache metadata-free auto review terminals

[cbusillo]

Summary

• remember terminal Auto Review agents even when missing metadata made the status non-authoritative
• allow a cached terminal agent to proceed later if it now matches an active background review state
• add a regression proving a metadata-free terminal status does not resurface after the active review clears

Validation

• cargo test -p code-tui --features test-helpers auto_review
• git diff --check
• ./build-fast.sh

Follow-up for the Auto Review finding after #307/#308.