* fix(store): debounce container change notifications to avoid reconcile storms
SubscribeContainers forwarded every raw row-level change event from
Corrosion as its own signal, with no coalescing. Each signal triggers
a full reconcile (ListContainers + regenerate) in every independent
subscriber (caddy-controller, DNS resolver) on every machine in the
cluster. With enough container/health-check churn across services,
this produces a sustained stream of events (observed ~1.6-1.7/sec
cluster-wide on a 45-service, 7-machine cluster) and burns meaningful
CPU on every machine continuously, regardless of whether that machine
runs Caddy locally. On a resource-constrained node this escalated into
kernel RCU stall warnings and a full freeze.
Coalesce bursts of events into a single signal per debounce window
instead of forwarding one per event.
* bound debounced changes by the window
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Co-authored-by: Pasha Sviderski <me@psviderski.name>
