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. Forward-compatible raw JSON consumers should accept unknown fields within known kinds and treat unknown span_type/log_type values generically. Top-level unknown-kind handling varies by interface and SDK version; do not assume every generated SDK exposes an UnknownFrame variant. Live readers should accept either a single frame object or an array for forward compatibility; current first-party forwarding normally sends one frame object per message.