Initial rebrand: @polkadot -> @pezkuwi (14 packages)

- Package namespace: @polkadot/* -> @pezkuwi/*
- Repository: polkadot-js/common -> pezkuwichain/pezkuwi-common
- Author: Pezkuwi Team <team@pezkuwichain.io>

Core packages:
- @pezkuwi/util (utilities)
- @pezkuwi/util-crypto (crypto primitives)
- @pezkuwi/keyring (account management)
- @pezkuwi/networks (chain metadata)
- @pezkuwi/hw-ledger (Ledger hardware wallet)
- @pezkuwi/x-* (10 polyfill packages)

Total: 14 packages
Upstream: polkadot-js/common v14.0.1

packages/util/src/is/childClass.ts

@@ -0,0 +1,29 @@
+// Copyright 2017-2025 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import type { Class } from '../types.js';
+
+import { isClass } from './class.js';
+
+/**
+ * @name isChildClass
+ * @summary Tests if the child extends the parent Class
+ * @description
+ * Checks to see if the child Class extends the parent Class
+ * @example
+ * <BR>
+ *
+ * ```javascript
+ * import { isChildClass } from '@pezkuwi/util';
+ *
+ * console.log('isChildClass', isChildClass(BN, BN); // => true
+ * console.log('isChildClass', isChildClass(BN, Uint8Array); // => false
+ * ```
+ */
+export function isChildClass <P extends Class> (Parent: P, Child?: unknown): Child is P {
+  // https://stackoverflow.com/questions/30993434/check-if-a-constructor-inherits-another-in-es6/30993664
+  return isClass(Child) && isClass(Parent)
+    // eslint-disable-next-line no-prototype-builtins
+    ? Parent === Child || Parent.isPrototypeOf(Child)
+    : false;
+}