List a session's telemetry frames

Returns the paginated telemetry frames for a session in the canonical frame envelope: one completed span frame per durable span (operations that never completed appear via their synthesized failed closures) plus log frames, ordered by span start / log time, with response-level billed-cost maps. This is the same envelope the live telemetry event stream (GET /realtime/sessions/{session_id}/events) carries; live and archive differ only in cardinality (start+end frames live, one completed frame here). Org-scoped: another org's session reads as not found. A trace past the organization's telemetry retention window returns an empty list with retention_expired=true; when the retention policy itself cannot be resolved the request fails with a 500 rather than serving frames whose retention state is unknown. Tolerant reader (unified frame contract): consumers MUST ignore frames with an unknown kind, unknown fields within known kinds, and unknown span_type/log_type values (render generically, never error). Generated SDK types surface an unrecognized frame as an explicit UnknownFrame variant carrying the raw JSON, never a silent drop. A live-stream message MAY carry a JSON array of frame objects; consumers MUST accept a single object or an array.