fix: close out remaining audit findings — type safety, equivalence, deprecations

lower-to-canonical.ts: clauseEquivalent now compares compoundOperator
  and compoundGroupId. Previously, compound assertions with different
  operators (.and vs .or) were considered equivalent.

fol-compiler.ts: adaptGrammarFormulaToLogicAst validates node.kind
  against known formula kinds (forall/exists/and/or/not/implies/predicate)
  before passing through as FormulaNode. Previously any object with a
  'kind' property was blindly cast.

predicates.ts / registry.ts: @deprecated tags on globalPredicateRegistry
  and globalClauseRegistry. Both are still functional but consumers should
  transition to explicit injection via LogicEngineOptions / EvaluationOptions.

454 solver+DSL tests pass, zero regressions.

packages/imhotep-dsl/src/lower-to-canonical.ts

@@ -616,6 +616,8 @@ export function clauseEquivalent(a: CanonicalClauseDescriptor, b: CanonicalClaus
     a.flags === b.flags &&
     a.quantifier === b.quantifier &&
     a.envGuard === b.envGuard &&
+    a.compoundOperator === b.compoundOperator &&
+    a.compoundGroupId === b.compoundGroupId &&
     frameEquivalent(a.frame, b.frame) &&
     stateEquivalent(a.state, b.state) &&
     toleranceEquivalent(a.tolerance, b.tolerance) &&