add linter for checking license headers (and eslint --fix target to match, and fix missing license headers while we're here) (#62)

packages/cli/src/ui/colors.ts

@@ -1,3 +1,9 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 export const Colors = {
   Background: '#1E1E2E',
   Foreground: 'white',

packages/cli/src/ui/hooks/useStdin.ts

@@ -1,3 +1,9 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 import { useState, useEffect } from 'react';
 import { useStdin } from 'ink';