Delete Call Review

Delete the current user's review (+ its annotations + its findings).

Sequence (single transaction, auto-committed by managed_session):

1. Truncate the review's annotations so sync_review_to_findings runs its "cart stays empty" branch — soft-dismisses every finding this review ever produced. The review row must still exist at this point because the sync function filters findings by raw_payload.voice_call_review_id == review.id.
2. Delete the review row (FK cascade drops the now-empty annotation set) and reconcile call-level outcome: re-project from the most recently updated remaining review, or revert to unreviewed if none.
3. managed_session commits on success / rolls back on exception.

Soft-dismissed findings (never hard-deleted) preserve the audit trail for V0.6's rationale attribution.