Lifecycle states - Stash

The candidate state machine rejects every transition not listed below with invalid_transition.

Current state	Event	Next state
`proposed`	`begin_screening`	`screening`
`proposed`	`quarantine`	`quarantined`
`proposed`	`reject`	`rejected`
`screening`	`screening_passed`	`evaluating`
`screening`	`begin_evaluation`	`evaluating`
`screening`	`quarantine`	`quarantined`
`screening`	`reject`	`rejected`
`screening`	`provider_failed`	`failed`
`evaluating`	`evaluation_passed`	`review_required`
`evaluating`	`request_review`	`review_required`
`evaluating`	`quarantine`	`quarantined`
`evaluating`	`reject`	`rejected`
`evaluating`	`provider_failed`	`failed`
`review_required`	`approve`	`approved`
`review_required`	`reject`	`rejected`
`review_required`	`quarantine`	`quarantined`
`approved`	`activate`	`active`
`approved`	`reject`	`rejected`
`active`	`supersede`	`superseded`
`active`	`roll_back`	`rolled_back`
`active`	`expire`	`expired`

Terminal states

quarantined, rejected, superseded, rolled_back, expired, and failed have no outgoing candidate transitions. Restoring a historical payload creates a new version and revision; it does not transition a terminal row back to active.