docs(app): implement AI search

docs/app/composables/useHighlighter.ts

@@ -0,0 +1,21 @@
+import { createHighlighter, type HighlighterGeneric } from 'shiki'
+import { createJavaScriptRegexEngine } from 'shiki/engine-javascript.mjs'
+
+let highlighter: HighlighterGeneric<any, any> | null = null
+
+let promise: Promise<HighlighterGeneric<any, any>> | null = null
+
+export const useHighlighter = async () => {
+  if (!promise) {
+    promise = createHighlighter({
+      langs: ['vue', 'js', 'ts', 'css', 'html', 'json', 'yaml', 'markdown', 'bash'],
+      themes: ['material-theme-palenight', 'material-theme-lighter'],
+      engine: createJavaScriptRegexEngine()
+    })
+  }
+  if (!highlighter) {
+    highlighter = await promise
+  }
+
+  return highlighter
+}