Hermetic CPU coverage for diffusion_te_prequant: the checkpoint
filename convention, family-table resolution by scheme and component
with malformed entries skipped, resolution priority (path override,
hosted repo, none) and the fp8-only scheme gate, the checkpoint
validation matrix (wrong format, missing state_dict, wrong scheme,
wrong component, wrong or missing base_model_id) with base case
folding, the local-path allowlist refusal and missing-file fallback,
and the assembly injection gating (mode, hosted entry, device support,
family deny, load failure, successful injection). Also pins the
te_prequant_repos field on both family dataclasses and that no family
ships a hosted TE checkpoint until the campaign wires one.
