Update copyright headers to 2026

The header rule in @pezkuwi/dev requires the current year. Year range only; the third-party beachball LICENSE is left as it is.

packages/ui-keyring/src/Keyring.ts

@@ -1,4 +1,4 @@
-// Copyright 2017-2025 @pezkuwi/ui-keyring authors & contributors
+// Copyright 2017-2026 @pezkuwi/ui-keyring authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
 import type { KeyringPair, KeyringPair$Json, KeyringPair$Meta } from '@pezkuwi/keyring/types';