wasmCloud 2.4.0: HPA + KEDA autoscaling, multi-handler workloads, pluggable NATS

wasmCloud 2.4.0 adds Kubernetes-native autoscaling for Wasm workloads via HPA and KEDA, multi-handler messaging in wash dev, and a Helm chart NATS overhaul with split scheduler and data URLs. It also introduces a NATS-backed operator liveness probe and bumps Wasmtime to 45.0.2 for a security fix.