Builds structured metadata maps for logging and tracing ledger operations.

Implementations focus on command-centric structs (commands and command maps) while accepting related domain entities or errors to enrich the metadata. Keys are prefixed with event_* for backward compatibility with existing log consumers, but values describe command activity.

The metadata includes a trace_context field that propagates the consumer-supplied distributed tracing context (e.g. W3C traceparent/tracestate) into Logger metadata, enabling correlation with upstream request spans.