v27.0.0

• Adopt SemanticConventions 13.1.1: native typed application attributes replace SetAppTag and its forced prefix. Generated starters remain optional; consumers can register their own activity sources.
• Verify both generated and application-owned sources through real packaged consumers and the public host pipeline. Use Testing 3.0.1 for HTTP and gRPC receivers, configurable bounded payloads, reliable cancellation and retained raw captures.
• Add CollectorProtocol for explicit collector endpoints. HTTP/protobuf remains the programmatic default; selecting native OtlpExportProtocol.Grpc works on any port. Remove the port-4317 transport guess and verify real hosts export all three signals through both transports.
• Advance the generated-code ABI to V27 so generator and runtime packages share the new major.
• Dispose the collector-discovery probe's wait handle, remove unused build helpers and meter constants, and keep process failure diagnostics with their elapsed time.