feat(third-door): wire high surprise to DiscoveryCandidate (#20 follow-up)
- Physics dual operators set discovery_eligible (γ=0.35); is_discovery_eligible
pure predicate; no teaching/vault imports in core.physics.surprise.
- teaching.discovery: trigger high_surprise; candidate_from_surprise_dual +
emit_surprise_discovery (opt-in sink, proposal-only unreviewed, domain=math).
- Boundary tests: threshold gates, determinism, no VaultStore, no teaching import
in physics. Ledger §6 notes wiring surface (issue #30).
Does not self-install; contemplation consumes via existing DiscoveryCandidateSink.
