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-playwright/src/fol-compiler.ts

@@ -36,12 +36,15 @@ import { FluentQuantifier as FQ, FluentRelation as FR } from 'imhotep-dsl'
  * - If the node has a `type` property, it's in grammar.ts shape and needs conversion.
  */
 function adaptGrammarFormulaToLogicAst(node: any): FormulaNode {
-  // Already in logic-ast.ts shape — pass through
   if (node && typeof node === 'object' && 'kind' in node) {
-    return node as FormulaNode
+    const kind = node.kind
+    if (kind === 'forall' || kind === 'exists' || kind === 'and' || kind === 'or' ||
+        kind === 'not' || kind === 'implies' || kind === 'predicate') {
+      return node as FormulaNode
+    }
+    throw new TypeError(`Unknown formula kind: ${kind}`)
   }
 
-  // Not an object or null — cannot adapt
   if (!node || typeof node !== 'object') {
     throw new TypeError('Cannot adapt non-object formula node')
   }