feat(workflow): add WorkflowListener bridging events → runner

[mpge]

Summary

Final piece of the workflow stack for Spring. The listener subscribes to the existing ApplicationEvent types (TicketEvent, ReplyEvent) and routes each to the canonical workflow trigger name, then delegates to WorkflowRunnerService.runForEvent.

Behavior

• @Async — a slow workflow never blocks the mutation that fired it
• Event → trigger mapping matches WorkflowEngine.TRIGGER_EVENTS:
  • CREATED → ticket.created
  • UPDATED → ticket.updated
  • ASSIGNED → ticket.assigned
  • STATUS_CHANGED / CLOSED / RESOLVED → ticket.status_changed
  • PRIORITY_CHANGED → ticket.priority_changed
  • REOPENED → ticket.reopened
  • ReplyEvent.CREATED → reply.created
• MERGED / SPLIT / SNOOZED / UNSNOOZED / DELETED silently ignored (not in the canonical 12-event set)

Complete chain

With this PR the workflow flow is end-to-end:

TicketService mutation → ApplicationEvent
  → WorkflowListener.onTicketEvent / onReplyEvent
  → WorkflowRunnerService.runForEvent
  → WorkflowEngine (conditions) + WorkflowExecutorService (actions)
  → WorkflowLog audit row

Dependencies

• Stacked on feat(workflow): add WorkflowRunnerService for event-driven workflow firing #22 (feat/workflow-runner), which is stacked on feat(workflow): add WorkflowExecutorService for action dispatch #21 (feat/workflow-executor).
• Merge order: feat(workflow): add WorkflowExecutorService for action dispatch #21 → feat(workflow): add WorkflowRunnerService for event-driven workflow firing #22 → this PR.

Test plan

• 12 unit tests covering every event-type → trigger mapping + the ignored cases
• CI green (won't trigger against stacked base until rebased)