js-rigor: possibilistic validity layer (Cella FVN labels, conflict mass, validification)

Adds an epistemic validity layer in the spirit of the zig-contour fusion
spec: every check result now carries a validity block {label, operator,
regime, sources, conflictMass, validifiedPossibility, nonMaxitive}.

- Relations accept a validity label (default heuristic = unlabeled input).
- Labels propagate through fusion: identity/max preserve the weakest
  source label (max is already valid under arbitrary dependence); min
  (conjunctive: intersection, chain, TTU, multi_hop, parent) is
  approximate at best, surfaces the conflict mass (1 - possibility) that
  was previously dropped, and exposes the arbitrary-regime validification
  min(1, K*gamma); product-style operators (exclusion, defeasible) and
  interior OWA averaging are always heuristic, with nonMaxitive flagged.
- Reliability and validity are now explicitly distinct: reliability stays
  the scalar confidence adaptation; validity tracks the epistemic label.
- The hottest paths attach a shared frozen default block instead of
  allocating (perf A/B shows no regression: ~300k ops/s direct both ways).
- Pre-existing fixes surfaced while wiring: the array-form logical config
  dropped top-level aggregator/owaWeights (average union compiled as max),
  and _createStandardResult dropped unknown fields (validity never
  survived rule results).

New campaign validity-parity.test.js pins the label taxonomy, conflict
mass, validification, weakest-propagation, and the reliability/validity
separation. Suites: rigor 203/0, full 803/741/0.

src/authorization/rules/ChainRule.js

@@ -350,6 +350,7 @@ export class ChainRule extends BaseRule {
     const authResult = {
       possibility: finalPossibility,
       reliability: finalReliability,
+      validity: this._validity('min', normalizedRule.steps.map(s => s.relation).filter(Boolean), [], normalizedRule.steps.length, finalPossibility),
       ...(includeMeta && {
         meta: finalPossibility > 0 ? {
           ruleType: 'chain',