• Merge pull request #1305 from zingolabs/version-bump-0.4.2-rc.1
• Bump versions for 0.4.2-rc.1
• Merge pull request #1294 from zingolabs/feature/metrics-and-tracing
• Refactor metrics: dedupe emission into helpers, single-source metric names
• Add comprehensive metrics: sync lifecycle, gRPC, outbound RPC, mempool
• Use structured tracing fields across all crates
• Add Prometheus /metrics endpoint behind prometheus feature flag