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/observable.spec.ts

@@ -0,0 +1,26 @@
+// Copyright 2017-2025 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+/// <reference types="@polkadot/dev-test/globals.d.ts" />
+
+import { isObservable } from './index.js';
+
+describe('isObservable', (): void => {
+  it('returns true on valid observables', (): void => {
+    expect(
+      isObservable({ next: (): boolean => true })
+    ).toEqual(true);
+  });
+
+  it('returns false on invalid objects', (): void => {
+    expect(
+      isObservable('notAnObservable')
+    ).toEqual(false);
+  });
+
+  it('returns false on invalid next functions', (): void => {
+    expect(
+      isObservable({ next: true })
+    ).toEqual(false);
+  });
+});