Get everything flagged on a trace

Returns every detection on one trace, per family (emotion, laziness, hallucination, tool_failure, custom_signal), each with its message anchor (conversation_id, msg_index), plus the Problems the trace is evidence for (id, title, attribution count). No time window. Each family reports detector.enabled (the workspace processing switch, null when there is none) and processed (whether this trace has been through the detector, null when that is not recorded), so an empty family can be told apart from one that did not run.