moq-relay-ietf-v0.7.11

Added

• add additional debug logging for troubleshooting
• add structured fields to high-value log messages
• (metrics) add describe_metrics() for Prometheus HELP text
• (metrics) distinguish graceful close from connection errors
• (moq-relay-ietf) add optional prometheus exporter for metrics validation
• (moq-relay-ietf) add metrics instrumentation via metrics crate facade

Fixed

• cargo fmt and clippy lints
• (metrics) move upstream_connections gauge after successful connect
• (metrics) address review feedback for metrics instrumentation

Other

• migrate from log crate to tracing
• (metrics) make metrics always-on, remove feature gate