SwimTelemetry observer records probe RTTs (p50), recent targets, and membership
transitions for the node's telemetry tick. Expand registry/registry_actor, datastream
catalog/emit/source, and the pipeline-parallel cluster/fleet. Wire the node main loop
to emit host/runtime/transport/membership frames.
Signed-off-by: Zachery Aaron Shores-Chmielewski <zacheryasc@gmail.com>