Sprint SPRINT_20260408_004 AUDIT-004 (retention enforcement).
AuditRetentionPurgeService BackgroundService enumerates tenants that
have any rows in timeline.unified_audit_events, then calls
timeline.purge_expired_audit_events(tenantId, dryRun) per tenant.
The SQL function honours per-classification retention windows and the
compliance_hold flag (legal holds pass through unaffected).
AuditRetentionPurgeOptions bound from the AuditRetentionPurge config
section: Enabled (default true), DryRun (default false), InitialDelay
(default 5 min), Interval (default 6h). Failures on a single tenant
are logged and do not stop the rest of the cycle.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
efc3500f20
