add base64 encoding/decoding

src/pages/tools/string/base64/meta.ts

@@ -0,0 +1,13 @@
+import { defineTool } from '@tools/defineTool';
+import { lazy } from 'react';
+
+export const tool = defineTool('string', {
+  name: 'Base64',
+  path: 'base64',
+  icon: 'mdi:code-tags',
+  description:
+    'A simple tool to encode or decode data using Base64, which is commonly used in web applications.',
+  shortDescription: 'Encode or decode data using Base64.',
+  keywords: ['base64'],
+  component: lazy(() => import('./index'))
+});