ObservedClassificationService

Opt-in observations for classification, with the delegate's metadata and model family preserved. Each call emits embabel.ai.classification with fixed operation and outcome tags and validates the selected category against the request. Provider observations inherit the open call scope. Payloads, model identifiers and raw exceptions are never added to these observations or debug logs. Operational failures and thrown exceptions record a fixed, stackless error marker with no cause. The original exception is rethrown unchanged; the wrapper never changes thread interruption state. Non-fatal observation lifecycle exceptions use bounded diagnostics when logging is available and never replace service behavior. JVM error types propagate.