chore: add playground theme example

Author: ThimoDEV

playground/app.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { javascript } from '@codemirror/lang-javascript'
 import { lineNumbersRelative } from '@uiw/codemirror-extensions-line-numbers-relative'
+import { okaidia } from '@uiw/codemirror-theme-okaidia';
 
 import type { ViewUpdate } from '@codemirror/view'
 import type { CodeMirrorRef, Statistics } from '../src/runtime/types/nuxt-codemirror'
@@ -45,7 +46,7 @@ onMounted(() => {
     v-model="code"
     :extensions="extensions"
     style="width: 500px; height: 400px;"
-    :theme="theme"
+    :theme="okaidia"
     placeholder="Enter your code here..."
     :auto-focus="true"
     :editable="true"

playground/package.json

@@ -11,6 +11,7 @@
     "@codemirror/lang-javascript": "^6.2.2",
     "@nuxt/kit": "^3.12.4",
     "@uiw/codemirror-extensions-line-numbers-relative": "^4.23.0",
+    "@uiw/codemirror-theme-okaidia": "^4.23.0",
     "nuxt": "^3.12.4"
   }
 }