Span Attribute Audit

Hold spans to an attribute convention the caller states, including per span kind. The finding that matters most: a span name embedding an identifier. The name is the aggregation key, so a name per call means every call is its own operation and no latency distribution exists for it; identifiers belong in attributes. Also reports a required attribute absent, an attribute the contract forbids, reported by key and never by value, and an unrecognised span kind.