ptone
Part of ptone/scion#1956. The GKE start-latency investigation found that the biggest attribution gap is instrumentation: the broker logs phase markers but no durations for scheduling, pull, syncs or execs, and nothing reports pod lifecycle timing or step-level timing inside sciontool init. This issue tracks adding structured elapsed_ms/bytes log fields (no behavior changes) so a live tester can attribute start time phase by phase from hub, broker and agent logs without kubectl. Scope: pod lifecycle timing on pod-ready, per-phase timing in the Kubernetes runtime's Run (including a sync/chown time split and tar sync byte counts), per-exec duration, broker provisioning and skill-fetch timing, hub buildCreateRequest timing, and sciontool init step timing with startup_ms surfaced to the hub.