refactor: use isObject from socket-registry instead of local implementation

Replace local isObject implementation with the identical one from @socketsecurity/registry/lib/objects to reduce code duplication. This doesn't inflate the build as rollup just creates a re-export reference to the external module.

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Co-Authored-By: Claude <[email protected]>

Author: jdalton

src/objects.ts

@@ -2,14 +2,10 @@
  * @fileoverview Object utility functions for type checking and immutable object creation.
  * Provides object validation and recursive freezing utilities.
  */
-import { LOOP_SENTINEL } from './constants.js'
+// eslint-disable-next-line import-x/extensions -- External package, no .js extension needed
+import { isObject } from '@socketsecurity/registry/lib/objects'
 
-/**
- * Check if value is an object type.
- */
-function isObject(value: unknown): value is object {
-  return value !== null && typeof value === 'object'
-}
+import { LOOP_SENTINEL } from './constants.js'
 
 /**
  * Recursively freeze an object and all nested objects.