Tempo 3.0 release: a new architecture for scale and lower TCO, TraceQL metrics GA, and more

Tempo 3.0 is a major release of the open source distributed tracing backend that introduces a Kafka-compatible architecture for microservices deployments. The new architecture separates read and write paths, eliminates the RF3 replication requirement (reducing storage to RF1), and replaces ingesters and compactors with block-builders, live-stores, and a backend scheduler. TraceQL metrics is now generally available, enabling ad-hoc metric queries directly from trace data with new comparison operator support. Other highlights include per-label cardinality limiting with HyperLogLog sketches, a DRAIN-based span name sanitizer, vParquet5 with doubled dedicated string columns, TraceQL AST query optimization, a new trace redaction CLI command for PII removal, and a migration tool to help upgrade from 2.x configurations.