Module rollback 

Rollback Engine for the Actuator

This module provides automatic and manual rollback capabilities with:

• Automatic rollback triggers (health, error rate, latency, quality, cost)
• Fast rollback mode (immediate revert)
• Gradual rollback (reverse canary phases)
• Configuration snapshot restoration
• State recovery and validation
• Rollback history tracking
• Notification support

Structs

RollbackEngine

Rollback Engine implementation

RollbackHistoryEntry

Rollback history entry

RollbackNotification

Rollback notification

RollbackPhase

Rollback phase for gradual rollback

RollbackStats

Rollback engine statistics

RollbackStatus

Rollback execution status

RollbackTrigger

Rollback trigger details

ThresholdViolation

Threshold violation details

Enums

NotificationSeverity

Notification severity

RollbackMode

Rollback mode

Traits

NotificationHandler

Trait for notification handlers