feat(masfeat): add MAS FEAT compliance types

Add MAS FEAT (Singapore MAS) compliance types:

Enums:
- MaterialityClassification (high/medium/low)
- SystemStatus (draft/active/suspended/retired)
- FEATAssessmentStatus (pending/in_progress/completed/approved/rejected)
- KillSwitchStatus (enabled/disabled/triggered)
- AISystemUseCase (credit_scoring, robo_advisory, etc.)

Request/Response Types (all with Builder pattern):
- RegisterSystemRequest, AISystemRegistry, RegistrySummary
- CreateAssessmentRequest, UpdateAssessmentRequest, FEATAssessment
- ConfigureKillSwitchRequest, CheckKillSwitchRequest, KillSwitch
- ApproveAssessmentRequest, RejectAssessmentRequest
- TriggerKillSwitchRequest, RestoreKillSwitchRequest
- KillSwitchEvent

Enterprise Feature: Requires AxonFlow Enterprise license.

Author: saurabhjain1592