fix(examples): wire online kv-events ZMQ subscriber

[Iceber]

Summary

This PR fixes the online KV events example used by the Helm kv-cache-manager deployment

Previously, the online manager started the KV events pool but never created a ZMQ subscriber, so vLLM KV cache events published to ZMQ_ENDPOINT were not ingested. The manager could still serve HTTP scoring endpoints, but its KV block index would not be updated from runtime events.

The fix wires SubscriberManager into the online startup path:

• reads the KV events config once in run
• starts the events pool
• creates a static ZMQ subscriber for ZMQ_ENDPOINT / ZMQ_TOPIC
• shuts down the subscriber manager and pool during graceful shutdown

[github-actions]

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[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR adds explicit setup/teardown for a static ZMQ subscriber alongside the existing KV events pool, making subscription management more explicit in the online KV events example.

Changes:

• Pass a shared kvevents.Config into setupEventsPool rather than creating it inside the helper.
• Introduce setupEventsSubscriber to create/manage a static ZMQ subscriber via kvevents.SubscriberManager.
• Ensure shutdown now includes subscriber manager shutdown before shutting down the events pool.

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[yankay]

Thanks for fixing this. The subscriber wiring matches the Helm kv-cache-manager path, and CI is green.
/lgtm