framework/contracts

Why

Break reverse edges: storage/processing must not import telemetry types and vice versa.

Modules

File	Purpose
saturation_slices.py	saturation / homogeneity slices
dataset_metric_rows.py	rows for evaluate metrics
worker_metric_delta.py	multi-worker metric deltas

Rule: new shared structures across layers go here — no I/O, no prometheus_client.