advertiseCapabilities

Advertise the capabilities this peer serves — GPU, region, held datasets, runtime, memory class — as an opaque CapSet. Publishes into this peer's own slot of the capability board, folds it into the local TTL tracker, and broadcasts it best-effort over the capability channel (H8, design §14.6).

A task carrying an Affinity is then placed only on peers whose advertised CapSet satisfies it (see eligiblePeers / TaskRing.owner). Advertisement is soft state, not authority: it can be stale, duplicated, or lost, and the worst outcome is a task briefly misplaced — absorbed by the Results dedup and ring re-home. It never authorizes anything; eligibility introduces no conserved quantity, so it cannot touch conservation.

Re-advertise periodically to keep the slot live — a slot that stops refreshing ages out after capabilityTtl. Passing CapSet.EMPTY makes this peer eligible only for Affinity.Anywhere work.