Hard-gate missing evaluator evidence before judge fusion

For hybrid evaluators, deterministic missing-evidence results should be treated as hard gates before semantic judge fusion. Otherwise a judge can turn an unverifiable case into an apparent pass. Freeze adapter and rubric versions into the plan, validate public evidence references as value-free positional tokens, and let code adapters return controlled pass/fail/not_applicable/not_assessable outcomes that the judge cannot override when provenance, completeness, ordering, or policy evidence is missing.