feat(service): P4 doc-faithfulness — SLA placeholder columns, issueSubclass, traceId on state.changed

Adds ticket.slaDueAt + ticket.issueSubclass + queue.slaPolicyRef (placeholder
columns, no timer logic until P7) and propagates ticket.traceId onto
ticket.state.changed events (assignment + transition). 45 tests still green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/src/support/support.service.ts

@@ -123,7 +123,12 @@ export class SupportService {
       subject: `ticket/${ticketId}`,
       time: new Date().toISOString(),
       datacontenttype: 'application/json',
-      insignia: { scopeSnapshotId: ticket.scopeId, idempotencyKey: `ticketstate:${ticketId}:${toState}`, dataClass: 'internal' },
+      insignia: {
+        scopeSnapshotId: ticket.scopeId,
+        correlationId: ticket.traceId ?? undefined,
+        idempotencyKey: `ticketstate:${ticketId}:${toState}`,
+        dataClass: 'internal',
+      },
       data: { ticketId, fromState: ticket.state, toState },
     };
     const [updated] = await this.prisma.$transaction([